Electrical properties of III-V/oxideinterfaces         G. Brammertz, H.C. Lin, A. Alian, S. Sioncke, L. Nyns, C.         M...
Outline• Introduction: interface states• Electrical interface state characterization techniques:    •   Conductance method...
Interface states     Interface states arise from the sudden disruption of the lattice structure, which     creates carrier...
Charge trapping/emission at the interface     Interface defects are small localized potential wells at the surface of the ...
σ =10-14 cm2                                     Characteristic frequencies                                               ...
σ =10-16 cm2                                     Characteristic frequenciesCharacteristic trap frequency (Hz)             ...
σ =10-18 cm2                                     Characteristic frequencies                                               ...
Outline• Introduction: interface states• Electrical interface state characterization techniques:    •   Conductance method...
Conductance method                                            • Interface states induce an additional capacitance         ...
Conductance method: pitfalls*1. Depending on the size of the bandgap of   the material, only small portions of the   bandg...
Conductance method: pitfalls*3. Weak inversion responses, due to                                                    freque...
Terman method (high frequency CV)            Comparison of high frequency CV curve to                                     ...
Berglund method (low frequency CV)            Comparison of low frequency CV curve to                                     ...
Combined high-low frequency method          Derivation of Dit from both high and low                           1         ...
Full simulation of electrostatics  Solution of the Poisson equation,                         d 2 V(x)    ρ ( x)           ...
Full model*    Integrating the Poisson equation:         d 2V ( x)   dE ( x) e( N d − N a + p ( x ) − n ( x ) )           ...
Outline• Introduction: interface states• Electrical interface state characterization techniques:    •   Conductance method...
Dit distribution of GaAs with Al2O3 (S-pass. and FGA)*                                                         p-type     ...
Dit distribution of GaAs-amorphous oxide interfaces    GaAs-Gd2O3 (MBE)                    GaAs-HfO2 (ALD)            GaAs...
Physical identity of GaAs interface states:   Dangling bond states*Which defect peak corresponds to what physical defect? ...
Physical identity of GaAs interface states:   Oxygen bond states*Which defect peak corresponds to what physical defects?  ...
Physical identity of GaAs interface states:   Vacancies (Ga-Ga, As-As bonds)*Which defect peak corresponds to what physica...
GaAs/oxide interfaces that diverge considerably fromthis picture            GaAs-Ga2O-GGO1                                ...
Outline• Introduction: interface states• Electrical interface state characterization techniques:    •   Conductance method...
Dit distribution of In0.53Ga0.47As with Al2O3 (S-pass.) :                                  Conductance method*            ...
Dit distribution of In0.53Ga0.47As with Al2O3 (S-pass.): Conductance methodAnalysis of the trap properties:         Gp/Aωq...
Dit distribution of In0.53Ga0.47As with Al2O3 (S-pass.):Full electrostatic simulations*    n-In0.53Ga0.47As-Al2O3-Pt      ...
Comparison:Conductance method – electrostatic simulation*                                        40                       ...
Dit distribution of In0.53Ga0.47As-amorphous oxide interfaces                             InGaAs-Al2O3 (ALD)              ...
Effect of ALD precursor H2O vs O3                                                          n-In0.53Ga0.47As with HCl-clean...
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
IBM III-V workshop 2010
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IBM III-V workshop 2010

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Electrical properties of III-V oxide interfaces

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IBM III-V workshop 2010

  1. 1. Electrical properties of III-V/oxideinterfaces G. Brammertz, H.C. Lin, A. Alian, S. Sioncke, L. Nyns, C. Merckling, W.-E. Wang, M.Caymax, M. Meuris., M. Heyns., T. Hoffmann© IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD
  2. 2. Outline• Introduction: interface states• Electrical interface state characterization techniques: • Conductance method • Terman method • Berglund method • Combined high and low frequency method • Full simulation of electrostatics• GaAs/oxide interface properties• In0.53Ga0.47As/oxide interface properties• InP/oxide interface properties• Electrostatic effect of interface states on MOS-HEMT devices• Conclusions © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 2
  3. 3. Interface states Interface states arise from the sudden disruption of the lattice structure, which creates carrier energy levels different from the usual energy band structure. DOS Derived mainly Derived mainly from As from Ga wavefunctions wavefunctions EV EC Energy DOS~1015 cm-2 broken bonds ~1015 cm-2 interface states Donors Acceptors EV EC Energy © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 3
  4. 4. Charge trapping/emission at the interface Interface defects are small localized potential wells at the surface of the material, if their energy level lies within the bandgap. EC EC ∆E ∆E Eg Eg EV EV Charge trapping Charge emission  ∆E  1 exp  τt = τ e (∆E) =  kT  σv t N c σv t N c • The charge trapping time τt depends only on the capture cross section of the trap (σ), the thermal velocity (vt) and the density of states (Nc). • The charge emission time also depends exponentially on the trap depth ΔE. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 4
  5. 5. σ =10-14 cm2 Characteristic frequencies Characteristic trap frequency (Hz)Characteristic trap frequency (Hz) Characteristic trap frequency (Hz) 10 10 8 GaN 10 10 GaAs 10 InP 4 8 8 10 10 10 0 6 6 10 10 10 -4 10 4 10 4 10 -8 10 2 2 -12 10 10 10 0 0 -16 10 10 10 -2 -2 -20 10 10 10 0 0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 1.2 Energy in bandgap (eV) Energy in bandgap (eV) Energy in bandgap (eV) Characteristic trap frequency (Hz) Characteristic trap frequency (Hz)Characteristic trap frequency (Hz) 10 10 10 10 Si 10 In0.53Ga0.47As 10 InAs 8 8 8 10 10 10 6 6 6 10 10 10 4 4 4 10 10 10 2 2 2 10 10 10 0 0 0 10 10 10 -2 -2 -2 10 10 10 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0 0.2 Energy in bandgap (eV) Energy in bandgap (eV) Energy in bandgap (eV) The characteristic trap frequency varies strongly with the energy level of the trap in the bandgap, such that with typical AC measurement frequencies only small parts of the bandgap can be measured. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 5
  6. 6. σ =10-16 cm2 Characteristic frequenciesCharacteristic trap frequency (Hz) Characteristic trap frequency (Hz) Characteristic trap frequency (Hz) 10 10 10 8 GaN 10 GaAs 10 InP 4 8 8 10 10 10 0 10 6 6 10 10 -4 10 4 4 10 10 -8 10 2 2 -12 10 10 10 0 0 -16 10 10 10 -2 -2 10 -20 10 10 0 0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 1.2 Energy in bandgap (eV) Energy in bandgap (eV) Energy in bandgap (eV) Characteristic trap frequency (Hz)Characteristic trap frequency (Hz) Characteristic trap frequency (Hz) 10 10 10 10 Si 10 In0.53Ga0.47As 10 InAs 8 8 8 10 10 10 6 6 6 10 10 10 4 4 4 10 10 10 2 2 2 10 10 10 0 0 0 10 10 10 -2 -2 -2 10 10 10 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0 0.2 Energy in bandgap (eV) Energy in bandgap (eV) Energy in bandgap (eV) The characteristic trap frequency varies strongly with the energy level of the trap in the bandgap, such that with typical AC measurement frequencies only small parts of the bandgap can be measured. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 6
  7. 7. σ =10-18 cm2 Characteristic frequencies Characteristic trap frequency (Hz)Characteristic trap frequency (Hz) Characteristic trap frequency (Hz) 10 10 10 8 GaN 10 GaAs 10 InP 4 8 8 10 10 10 0 6 6 10 10 10 -4 10 4 10 4 10 -8 10 2 2 -12 10 10 10 0 0 -16 10 10 10 -2 -2 -20 10 10 10 0 0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 1.2 Energy in bandgap (eV) Energy in bandgap (eV) Energy in bandgap (eV) Characteristic trap frequency (Hz) Characteristic trap frequency (Hz)Characteristic trap frequency (Hz) 10 10 10 10 Si 10 In0.53Ga0.47As 10 InAs 8 8 8 10 10 10 6 6 6 10 10 10 4 4 4 10 10 10 2 2 2 10 10 10 0 0 0 10 10 10 -2 -2 -2 10 10 10 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0 0.2 Energy in bandgap (eV) Energy in bandgap (eV) Energy in bandgap (eV) The characteristic trap frequency varies strongly with the energy level of the trap in the bandgap, such that with typical AC measurement frequencies only small parts of the bandgap can be measured. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 7
  8. 8. Outline• Introduction: interface states• Electrical interface state characterization techniques: • Conductance method • Terman method • Berglund method • Combined high and low frequency method • Full simulation of electrostatics• GaAs/oxide interface properties• In0.53Ga0.47As/oxide interface properties• InP/oxide interface properties• Electrostatic effect of interface states on MOS-HEMT devices• Conclusions © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 8
  9. 9. Conductance method • Interface states induce an additional capacitance and loss contribution in the MOS structure, represented by Cit and Rit in parallel with the M O S depletion capacitance. • The capacitance and resistance of the interface traps will be measured only if the measurement frequency is equal to the characteristic trap frequency at the Fermi Ef level position. eVG f = 1 kHz α Dit Cd Cox Rs Cit Rit • In the example case, at Vg=1V, the Fermi level at the semiconductor surface passes through the trap level with a characteristic frequency of 1 kHz. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 9
  10. 10. Conductance method: pitfalls*1. Depending on the size of the bandgap of the material, only small portions of the bandgap can be measured with the conductance method. Performing measurements at lower and higher temperatures might help for characterizing larger parts of the bandgap (Beware of weak inversion effects!).2. The amplitude of the measured interface state conductance is limited by the oxide capacitance, such that the largest Dit that can be extracted is of the order of Cox/q. Dit values that approach this value will be strongly leveled off. *K. Martens et al., TED 55 (2), 547, 2008 © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 10
  11. 11. Conductance method: pitfalls*3. Weak inversion responses, due to frequencies shown interactions of minority carriers with 1kHz → 1MHz interface states, do behave similarly to 300K majority carrier interface state responses. This can lead to overestimation of the Dit, if one applies equations that only take majority carriers into account. 0.7 Capacitance (µF/cm ) 24. Flatband voltage determination for 0.6 100 Hz energy-voltage relationship extraction can 0.5 be very problematic if large frequency 0.4 dependent flatband voltage shift is present. 1 MHz 0.3 0.2 -3 -2 -1 0 1 2 3 Gate voltage (V) *K. Martens et al., TED 55 (2), 547, 2008 © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 11
  12. 12. Terman method (high frequency CV) Comparison of high frequency CV curve to  dψ  −1  C it (ψ s ) = C ox  s  − 1 − C s (ψ s ) theoretical CV curve without interface states:  dVg     High frequency CV-curve meaning in this case: 1. Interface states do not respond to the measurement frequency and do not add any capacitance. Characteristic trap frequency (Hz) 10 10 In0.53Ga0.47As • If there is a large density of fast interface states at the band edges or 10 8 even inside the conduction band of III-V semiconductors, this 6 10 4 10 condition for application of the method is not verified. 10 2 • f.ex. in the InGaAs case there is typically a large density of very fast Dit close 10 0 to the valence band as well as inside the conduction band. 10 -2 0 0.2 0.4 0.6 EV Energy in bandgap (eV) EC 2. Interface states do respond to the bias sweep, which leads to stretch out of the CV-curve. Characteristic trap frequency (Hz) 10 • If there is a large density of very slow interface states inside the III-V 10 8 GaAs 10 semiconductor bandgap, this condition for application of the method 10 6 is not verified. 10 4 2 10 • f.ex. in the GaAs case there is typically a large density of very slow Dit close to 10 0 mid-gap, which does not respond to the bias sweep. 10 -2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Energy in bandgap (eV) For pretty much all III-V/oxide interfaces, at least one of the conditions is not verified, such that this method will in most cases lead to errors in the derived Dit values. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 12
  13. 13. Berglund method (low frequency CV) Comparison of low frequency CV curve to  1 1  −1 C it =  −  − Cs theoretical CV curve without interface states:  C LF C ox  Low frequency CV-curve meaning in this case: 1. Interface states fully respond to the measurement frequency and add capacitance to the CV. 2. Interface states do respond to the bias sweep, which leads to stretch out of the CV-curve. • If there is a large density of very slow interface states inside the III-V Characteristic trap frequency (Hz) 10 10 8 GaAs semiconductor bandgap, this condition for application of the method 10 6 10 is not verified. 10 4 • f.ex. in the GaAs case there is typically a large density of very slow Dit close to 10 2 mid-gap, which does not respond to the bias sweep, unless very slow sweep is 10 0 -2 10 used. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Energy in bandgap (eV) Due to low conduction band density of states the theoretical Energy-Voltage curves are more complicated than in the Si case: • Not a limitation, just a complication that can be addressed by using the correct theoretical model including Fermi-Dirac statistics for carrier concentrations.For low bandgap materials (In0.53Ga0.47As, InAs, InSb,...) these conditions are typically verified, BUT: slow oxide traps can also introduce stretchout, which could falsify the results. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 13
  14. 14. Combined high-low frequency method Derivation of Dit from both high and low  1 −1 1   1 1  −1 C it =  −  − C − C  frequency CV curves.  C LF C ox   HF ox High and low frequency CV-curves need to verify the conditions of the Terman and Berglund methodrespectively, which makes this method very restrictive. For pretty much all III-V/oxide interfaces, at least one of the conditions is not verified, such that this method will in most cases lead to errors in the derived Dit values. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 14
  15. 15. Full simulation of electrostatics Solution of the Poisson equation, d 2 V(x) ρ ( x) 2 =− dx εs Including the correct carrier In thermal equilibrium concentrations for degenerate (Similar to Berglund method) semiconductors, including Fermi-Dirac • For low bandgap materials (In0.53Ga0.47As, InAs, statistics. InSb,...) these conditions are typically verified, BUT: slow oxide traps can also introduce stretchout, which could falsify the results. Ev Ei In0.53Electrons As Ga Trap response frequency (Hz) Vfb Ec 10 10 Holes 0.47 8 10 6 10 4 10 AC-CV 2 10 0 10 QS-CV -2 10 0.0 0.2 0.4 0.6 Trap energy within bandgap (eV) © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 15
  16. 16. Full model* Integrating the Poisson equation: d 2V ( x) dE ( x) e( N d − N a + p ( x ) − n ( x ) ) 2 π ∞ (E − EC )1 / 2 = E ( x) =− ,where n(V ( x) ) = N C ∫E dE dx 2 dV ( x) εs (kT )3 / 2 C 1 + e ( E −V ( x )) / kT yields: V ( x ) e( N d − N a + p(V ( x)) − n(V ( x)) ) E (V ( x) ) = 2Sign(V s ) ∫ψ − dV ( x) B εs .• Applying Gauss’ theorem from the bulk to the surface of the semiconductor gives: Vs Es = −Qs / ε s and accordingly: Q s (V s ) = −2Sign(V s ) ∫ψ − eε s ( N d − N a + p(V ( x)) − n(V ( x)) )dV ( x) B .• The semiconductor and interface state capacitances can be written as: C s (V s ) = − dQ s (V s ) and d (∫ Vs +∞ V Dit , D dE − ∫− ∞ Dit , A dE s ) respectively. dVs C it (V s ) = dV s• The total capacitance of the MOS structure: 1 1 1 = + C tot (V s ) C ox C s (V s ) + C it (V s ) .• Finally, gate voltage and surface potential are related through: Q s (V s ) Qit (V s ) VG = V s + φ m − φ s − C ox − C ox . OR, full self-consistent numerical solution of the Poisson equation for more complicated semiconductor heterostructures * G. Brammertz et al., APL 95, 202109 (2010) © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 16
  17. 17. Outline• Introduction: interface states• Electrical interface state characterization techniques: • Conductance method • Terman method • Berglund method • Combined high and low frequency method • Full simulation of electrostatics• GaAs/oxide interface properties• In0.53Ga0.47As/oxide interface properties• InP/oxide interface properties• Electrostatic effect of interface states on MOS-HEMT devices• Conclusions © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 17
  18. 18. Dit distribution of GaAs with Al2O3 (S-pass. and FGA)* p-type n-type 25°C 150°C 150°C 25°C 0.8 0.7 0.7 100Hz Capacitance (µF/cm )Capacitance (µF/cm ) Capacitance (µF/cm ) 2 100Hz2 2 Capacitance (µF/cm ) 0.7 100Hz 0.6 2 0.7 100Hz 0.6 0.6 0.5 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.4 0.3 0.3 0.3 1MHz 0.3 1MHz 0.2 1MHz 0.2 1MHz 0.2 0.1 -3 -2 -1 0 1 2 -2 -1 0 1 2 -2 -1 0 1 2 -2 -1 0 1 2 3 Gate voltage (V) Gate voltage (V) Gate voltage (V) Gate voltage (V) Measuring n- and p-type GaAs at both 25°C and 150°C shows the interface state distribution in the complete bandgap. *G. Brammertz et al., APL 93, 183504 (2008) © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 18
  19. 19. Dit distribution of GaAs-amorphous oxide interfaces GaAs-Gd2O3 (MBE) GaAs-HfO2 (ALD) GaAs-Al2O3 (ALD)Not shown here, but also measured and showing similar interface state distribution: • GaAs-Al2O3 (MBE) • GaAs-Ge-GeO2-Al2O3 (MBE) • GaAs-LaAlO3 (MBE) • GaAs-ZrO2 (ALD) • GaAs-In-In2O3-Al2O3 (MBE) The interface state distribution of the GaAs-amorphous oxide interface depends rather little on the nature and the deposition condition of the oxide. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 19
  20. 20. Physical identity of GaAs interface states: Dangling bond states*Which defect peak corresponds to what physical defect? GaAs-Al2O3 before FGA GaAs-Al2O3 after FGA EV EC EV EC As dangling bonds Ga dangling bonds As dangling bonds Ga dangling bonds passivated passivated H passivates dangling bond states. *G. Brammertz et al., APL 93, 183504 (2008) © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 20
  21. 21. Physical identity of GaAs interface states: Oxygen bond states*Which defect peak corresponds to what physical defects? Ga 3+ detectable GaAs-Al2O3 after FGA Ga 3+ not detectable EV EC Ga 3+ Remaining defects close to the conduction band seem to be due to Ga3+ oxidation state (Hinkle et al.). * C. Hinkle et al., APL 94, 162101 (2009). © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 21
  22. 22. Physical identity of GaAs interface states: Vacancies (Ga-Ga, As-As bonds)*Which defect peak corresponds to what physical defects? GaAs-Al2O3 after FGA Donor Acceptor EV EC As vacancy (Ga-Ga bond) Ga vacancy (As-As bond) The dominating mid-gap peaks, one donor-like, one acceptor-like, are likely due to structural defects at the interface (vacancies)* *W. E. Spicer et al., JVST 16(5), 1422 (1979). © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 22
  23. 23. GaAs/oxide interfaces that diverge considerably fromthis picture GaAs-Ga2O-GGO1 GaAs-aSi-HfO22 1.0 25°C 25°C Capacitance (µF/cm ) 2 0.8 0.6 0.4 0.2 -1.0 0.0 1.0 2.0 VG (V) 150°C 1.0 150°C Capacitance (µF/cm ) 2 0.8 0.6 0.4 0.2 -1.0 0.0 1.0 2.0 VG (V)1 M. Passlack 1 J. De Souza et al., APL 92, 153508 (2008). et al., EDL 30 (1), 2 (2009). M. Passlack et al., accepted by TED (2010). C. Marchiori et al., JAP 106, 114112, (2010). © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 23
  24. 24. Outline• Introduction: interface states• Electrical interface state characterization techniques: • Conductance method • Terman method • Berglund method • Combined high and low frequency method • Full simulation of electrostatics• GaAs/oxide interface properties• In0.53Ga0.47As/oxide interface properties• InP/oxide interface properties• Electrostatic effect of interface states on MOS-HEMT devices• Conclusions © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 24
  25. 25. Dit distribution of In0.53Ga0.47As with Al2O3 (S-pass.) : Conductance method* p-In0.53Ga0.47As-Al2O3-Pt n-In0.53Ga0.47As-Al2O3-Pt 300°K 300°K 77°K 77°K 0.7 Capacitance (µF/cm ) 0.7 2 100HzCapacitance (µF/cm ) 0.7 Capacitance (µF/cm )2 0.7 2 Capacitance (µF/cm ) 0.6 2 0.6 0.6 0.6 100Hz 0.5 0.5 0.5 0.5 0.4 0.4 0.4 0.3 0.3 0.4 0.3 1MHz 1MHz 0.2 0.2 -3 -2 -1 0 1 2 3 -2 -1 0 1 2 -2 -1 0 1 2 3 -3 -2 -1 0 1 Gate voltage (V) Gate voltage (V) Gate voltage (V) Gate voltage (V) 210°K 0.7 180°K Capacitance (µF/cm ) 2 Capacitance (µF/cm ) 0.6 2 0.6 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 -3.0 -2.0 -1.0 0.0 -2 -1 0 1 2 3 Gate voltage (V) Gate voltage (V) *H.C. Lin et al., Microelectronic Engineering 86, 1554 (2009) © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 25
  26. 26. Dit distribution of In0.53Ga0.47As with Al2O3 (S-pass.): Conductance methodAnalysis of the trap properties: Gp/Aωq-f of p-InGaAs at 25°C Schematic band diagram EC EF EV Vg = 0.5 V 0 EC + EF Vg = 0.1 V 0 EV Band bending fluctuations increase as the Fermi level approaches the valence band => donor-like interface states. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 26
  27. 27. Dit distribution of In0.53Ga0.47As with Al2O3 (S-pass.):Full electrostatic simulations* n-In0.53Ga0.47As-Al2O3-Pt p-In0.53Ga0.47As-Al2O3-Pt 40 Acceptor D it Donor Dit Dit (1012/eVcm 2) 30 20 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Ev E-Ev (eV) Ec Large acceptor-like Dit peak in the conduction band allows good fit of experimental quasi-static C-V data * G. Brammertz et al., APL 95, 202109 (2010) © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 27
  28. 28. Comparison:Conductance method – electrostatic simulation* 40 D it from electrostatic simulations 35 D it from conductance method 30 Dit (1012/eVcm 2) 25 20 15 10 5 0 0 0.2 0.4 0.6 0.8 1 Ev E-Ev (eV) Ec Conductance method Electrostatic simulations Horizontal errors arise from: Capture cross section uncertainty Gate metal work function uncertainty Vertical errors arise from: Cox limitation of conductance Cox limitation of capacitance Uncertainty on Cox value Uncertainty on Cox value Non-parabolic conduction band Charge quantization Within the error margins there is good agreement between the electrostatic simulation model and the conductance data * G. Brammertz et al., APL 95, 202109 (2010) © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 28
  29. 29. Dit distribution of In0.53Ga0.47As-amorphous oxide interfaces InGaAs-Al2O3 (ALD) InGaAs-HfO2 (ALD) InGaAs-Al2O3 (MBE) 40 40 40 Acceptor D it Acceptor D it Acceptor Dit 35 35 35 Donor Dit Donor Dit Donor Dit 30 30 30Dit (1012/eVcm 2) Dit (1012/eVcm 2) Dit (1012/eVcm 2) 25 25 25 20 20 20 15 15 15 10 10 10 5 5 5 0 0 0 0.2 0.4 0.6 0.8 1 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 E-Ev (eV) E-Ev (eV) E-Ev (eV) Not shown here, but also measured and showing similar interface state distribution: • InGaAs-Al2O3 (ALD, O3) • InGaAs-LaAlO3 (ALD, O3) • InGaAs-Ge-GeO2-Al2O3 (MBE) • InGaAs-GdAlO3 (ALD) • InGaAs-ZrO2 (ALD) The interface state distribution of the In0.53Ga0.47As-amorphous oxide interface depends rather little on the nature and the deposition conditions of the oxide. Nevertheless, Hf- and Zr-based oxides usually show higher Dit at the conduction band edge energy as compared to Al-, Gd- and La-based oxides. © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 29
  30. 30. Effect of ALD precursor H2O vs O3 n-In0.53Ga0.47As with HCl-clean and 10 nm ALD Al2O3 H2O ALD precursor O3 ALD precursor 0.8 0.8 Capacitance ( µ F/cm 2) Capacitance ( µ F/cm 2) 0.7 0.7 0.6 0.6 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 -3 -2 -1 0 1 2 3 -3 -2 -1 0 1 2 3 Gate voltage V g (V) Gate voltage V g (V) 40 40 Acceptor D it Acceptor D it 35 35 Donor D it Donor Dit 30 Dit (1012/eVcm 2) 30 Dit (1012/eVcm 2) 25 25 20 20 15 15 10 10 5 5 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 E-Ev (eV) E-Ev (eV) O3-based ALD increases the Dit at the conduction band edge energy as compared to H2O-based ALD © IMEC 2010 / CONFIDENTIAL G. Brammertz, PT/LDD 30
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