J. Semicond. > Volume 37 > Issue 4 > Article Number: 044003

Modeling on oxide dependent 2DEG sheet charge density and threshold voltage in AlGaN/GaN MOSHEMT

J. Panda , K. Jena , R. Swain and T. R. Lenka

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Abstract: We have developed a physics based analytical model for the calculation of threshold voltage, two dimensional electron gas (2DEG) density and surface potential for AlGaN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMT). The developed model includes important parameters like polarization charge density at oxide/AlGaN and AlGaN/GaN interfaces, interfacial defect oxide charges and donor charges at the surface of the AlGaN barrier. The effects of two different gate oxides (Al2O3 and HfO2) are compared for the performance evaluation of the proposed MOSHEMT. The MOSHEMTs with Al2O3 dielectric have an advantage of significant increase in 2DEG up to 1.2×1013 cm-2 with an increase in oxide thickness up to 10 nm as compared to HfO2 dielectric MOSHEMT. The surface potential for HfO2 based device decreases from 2 to -1.6 eV within 10 nm of oxide thickness whereas for the Al2O3 based device a sharp transition of surface potential occurs from 2.8 to -8.3 eV. The variation in oxide thickness and gate metal work function of the proposed MOSHEMT shifts the threshold voltage from negative to positive realizing the enhanced mode operation. Further to validate the model, the device is simulated in Silvaco Technology Computer Aided Design (TCAD) showing good agreement with the proposed model results. The accuracy of the developed calculations of the proposed model can be used to develop a complete physics based 2DEG sheet charge density and threshold voltage model for GaN MOSHEMT devices for performance analysis.

Key words: 2DEGAlGaNGaNheterojunctionMOSHEMTtrap capacitance

Abstract: We have developed a physics based analytical model for the calculation of threshold voltage, two dimensional electron gas (2DEG) density and surface potential for AlGaN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMT). The developed model includes important parameters like polarization charge density at oxide/AlGaN and AlGaN/GaN interfaces, interfacial defect oxide charges and donor charges at the surface of the AlGaN barrier. The effects of two different gate oxides (Al2O3 and HfO2) are compared for the performance evaluation of the proposed MOSHEMT. The MOSHEMTs with Al2O3 dielectric have an advantage of significant increase in 2DEG up to 1.2×1013 cm-2 with an increase in oxide thickness up to 10 nm as compared to HfO2 dielectric MOSHEMT. The surface potential for HfO2 based device decreases from 2 to -1.6 eV within 10 nm of oxide thickness whereas for the Al2O3 based device a sharp transition of surface potential occurs from 2.8 to -8.3 eV. The variation in oxide thickness and gate metal work function of the proposed MOSHEMT shifts the threshold voltage from negative to positive realizing the enhanced mode operation. Further to validate the model, the device is simulated in Silvaco Technology Computer Aided Design (TCAD) showing good agreement with the proposed model results. The accuracy of the developed calculations of the proposed model can be used to develop a complete physics based 2DEG sheet charge density and threshold voltage model for GaN MOSHEMT devices for performance analysis.

Key words: 2DEGAlGaNGaNheterojunctionMOSHEMTtrap capacitance



References:

[1]

Huang S, Jiang Q, Yang S. Mechanism of PEALD-grown AlN passivation for AlGaN/GaN HEMTs:compensation of interface traps by polarization charges[J]. IEEE Electron Device Lett, 2013, 34(2): 193.

[2]

Liu C, Chor E F, Tan L S. Investigations of HfO2/AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors[J]. Appl Phys Lett, 2006, 88(17): 173504.

[3]

Maeda N, Hiroki M, Watanabe N. Systematic study of insulator deposition effect (Si3N4, SiO2, AlN, and Al2O3) on electrical properties in AlGaN/GaN heterostructures[J]. Jpn J Appl Phys, 2007, 46(2): 547.

[4]

Green B M, Chu K K, Chumbes E M. The effect of surface passivation on the microwave characteristics of undoped AlGaN/GaN HEMT's[J]. IEEE Electron Device Lett, 2000, 21(6): 268.

[5]

Hori Y, Mizue C, Hashizume T. Process conditions for improvement of electrical properties of Al2O3/n-GaN structures prepared by atomic layer deposition[J]. Jpn J Appl Phys, 2010, 49(8R): 080201.

[6]

Ooyama K, Kato H, Miczek M. Temperature-dependent interface-state response in an Al2O3/n-GaN structure[J]. Jpn J Appl Phys, 2008, 47(7R): 5426.

[7]

Terman L M. An investigation of surface states at a silicon/silicon oxide interface employing metal oxide silicon diode[J]. Solid-State Electron, 1962, 5(5): 285.

[8]

Sghaier N, Trabelsi M, Yacoubi N. Traps centers and deep defects contribution in current instabilities for AlGaN/GaN HEMT's on silicon and sapphire substrates[J]. Microelectron J, 2006, 37(4): 363.

[9]

Tirado J M, Rojas J L S, Izpura J I. Trapping effects in the transient response of AlGaN/GaN HEMT devices[J]. IEEE Trans Electron Devices, 2007, 54(3): 410.

[10]

Kordos P, Donoval D, Floroviè M. Investigation of trap effects in AlGaN/GaN field-effect transistors by temperature dependent threshold voltage analysis[J]. Appl Phys Lett, 2008, 92(15): 152113.

[11]

Nicllian E H, Goetzberger A. The Si-SiO2 interface-electrical properties as determined by the metal-insulator-silicon-conductance technique[J]. Microelectron Reliab, 1968, 7(2): 164.

[12]

Ma X H, Zhu J J, Liao X Y. Quantitative characterization of interface traps in Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors by dynamic capacitance dispersion technique[J]. Appl Phys Lett, 2013, 103(3): 033510.

[13]

Ibbetson J P, Fini P T, Ness K D. Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistors[J]. Appl Phys Lett, 2000, 77(2): 250.

[14]

Ambacher O, Smart J, Shealy J R. Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N and Ga-face AlGaN/GaN hetero structures[J]. Appl Phys Lett, 1999, 85(6): 3222.

[15]

Kola S, Golio J M, Maracas G N. An analytical expression for Fermi level versus sheet carrier concentration for HEMT modeling[J]. IEEE Electron Device Lett, 1988, 9(3): 136.

[16]

Li M, Wang Y. 2-D analytical model for current-voltage characteristics and transconductance of AlGaN/GaN MODFETs[J]. IEEE Trans Electron Devices, 2008, 55(1): 261.

[17]

Jena K, Swain R, Lenka T R. Modeling and comparative analysis of DC characteristics of AlGaN/GaN HEMT and MOSHEMT devices[J]. International Journal of Numerical Modelling Electronic Networks Devices & Fields, 2015.

[18]

Jena K, Swain R, Lenka T R. Impact of barrier thickness on gate capacitance——modeling and comparative analysis of GaN based MOSHEMTs[J]. Journal of Semiconductors, 2015, 36(3): 0340031.

[19]

Jena K, Swain R, Lenka T R. Interface DOS dependent analytical model development for DC characteristics of normally-off AlN/GaN MOSHEMT[J]. Superlattices and Microstructures, 2015, 84: 54.

[20]

Jena K, Swain R, Lenka T R. Impact of oxide thickness on gate capacitance-modelling and comparative analysis of GaN-based MOSHEMTs[J]. Pramana-Journal of Physics, 2015.

[21]

Tapajna M, Cico K, Kuzmik J. Thermally induced voltage shift in capacitance-voltage characteristics and its relation to oxide/semiconductor interface states in Ni/Al2O3/InAlN/GaN heterostructures[J]. Semicond Sci Technol, 2009, 24(5): 035008.

[22]

ATLAS User's Manual of SILVACO Inc, V er. 5[J]. .

[23]

Robertson J, Falabretti B. Band offset of high k gate oxides on Ⅲ-V semiconductors[J]. J Appl Phys, 2006, 100(1): 014111.

[24]

Ganguly S, Verma J, Li G. Presence and origin of interface charges at atomic-layer deposited Al2O3/Ⅲ-nitride hetero junctions[J]. Appl Phys Lett, 2011, 99(19): 193504.

[1]

Huang S, Jiang Q, Yang S. Mechanism of PEALD-grown AlN passivation for AlGaN/GaN HEMTs:compensation of interface traps by polarization charges[J]. IEEE Electron Device Lett, 2013, 34(2): 193.

[2]

Liu C, Chor E F, Tan L S. Investigations of HfO2/AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors[J]. Appl Phys Lett, 2006, 88(17): 173504.

[3]

Maeda N, Hiroki M, Watanabe N. Systematic study of insulator deposition effect (Si3N4, SiO2, AlN, and Al2O3) on electrical properties in AlGaN/GaN heterostructures[J]. Jpn J Appl Phys, 2007, 46(2): 547.

[4]

Green B M, Chu K K, Chumbes E M. The effect of surface passivation on the microwave characteristics of undoped AlGaN/GaN HEMT's[J]. IEEE Electron Device Lett, 2000, 21(6): 268.

[5]

Hori Y, Mizue C, Hashizume T. Process conditions for improvement of electrical properties of Al2O3/n-GaN structures prepared by atomic layer deposition[J]. Jpn J Appl Phys, 2010, 49(8R): 080201.

[6]

Ooyama K, Kato H, Miczek M. Temperature-dependent interface-state response in an Al2O3/n-GaN structure[J]. Jpn J Appl Phys, 2008, 47(7R): 5426.

[7]

Terman L M. An investigation of surface states at a silicon/silicon oxide interface employing metal oxide silicon diode[J]. Solid-State Electron, 1962, 5(5): 285.

[8]

Sghaier N, Trabelsi M, Yacoubi N. Traps centers and deep defects contribution in current instabilities for AlGaN/GaN HEMT's on silicon and sapphire substrates[J]. Microelectron J, 2006, 37(4): 363.

[9]

Tirado J M, Rojas J L S, Izpura J I. Trapping effects in the transient response of AlGaN/GaN HEMT devices[J]. IEEE Trans Electron Devices, 2007, 54(3): 410.

[10]

Kordos P, Donoval D, Floroviè M. Investigation of trap effects in AlGaN/GaN field-effect transistors by temperature dependent threshold voltage analysis[J]. Appl Phys Lett, 2008, 92(15): 152113.

[11]

Nicllian E H, Goetzberger A. The Si-SiO2 interface-electrical properties as determined by the metal-insulator-silicon-conductance technique[J]. Microelectron Reliab, 1968, 7(2): 164.

[12]

Ma X H, Zhu J J, Liao X Y. Quantitative characterization of interface traps in Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors by dynamic capacitance dispersion technique[J]. Appl Phys Lett, 2013, 103(3): 033510.

[13]

Ibbetson J P, Fini P T, Ness K D. Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistors[J]. Appl Phys Lett, 2000, 77(2): 250.

[14]

Ambacher O, Smart J, Shealy J R. Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N and Ga-face AlGaN/GaN hetero structures[J]. Appl Phys Lett, 1999, 85(6): 3222.

[15]

Kola S, Golio J M, Maracas G N. An analytical expression for Fermi level versus sheet carrier concentration for HEMT modeling[J]. IEEE Electron Device Lett, 1988, 9(3): 136.

[16]

Li M, Wang Y. 2-D analytical model for current-voltage characteristics and transconductance of AlGaN/GaN MODFETs[J]. IEEE Trans Electron Devices, 2008, 55(1): 261.

[17]

Jena K, Swain R, Lenka T R. Modeling and comparative analysis of DC characteristics of AlGaN/GaN HEMT and MOSHEMT devices[J]. International Journal of Numerical Modelling Electronic Networks Devices & Fields, 2015.

[18]

Jena K, Swain R, Lenka T R. Impact of barrier thickness on gate capacitance——modeling and comparative analysis of GaN based MOSHEMTs[J]. Journal of Semiconductors, 2015, 36(3): 0340031.

[19]

Jena K, Swain R, Lenka T R. Interface DOS dependent analytical model development for DC characteristics of normally-off AlN/GaN MOSHEMT[J]. Superlattices and Microstructures, 2015, 84: 54.

[20]

Jena K, Swain R, Lenka T R. Impact of oxide thickness on gate capacitance-modelling and comparative analysis of GaN-based MOSHEMTs[J]. Pramana-Journal of Physics, 2015.

[21]

Tapajna M, Cico K, Kuzmik J. Thermally induced voltage shift in capacitance-voltage characteristics and its relation to oxide/semiconductor interface states in Ni/Al2O3/InAlN/GaN heterostructures[J]. Semicond Sci Technol, 2009, 24(5): 035008.

[22]

ATLAS User's Manual of SILVACO Inc, V er. 5[J]. .

[23]

Robertson J, Falabretti B. Band offset of high k gate oxides on Ⅲ-V semiconductors[J]. J Appl Phys, 2006, 100(1): 014111.

[24]

Ganguly S, Verma J, Li G. Presence and origin of interface charges at atomic-layer deposited Al2O3/Ⅲ-nitride hetero junctions[J]. Appl Phys Lett, 2011, 99(19): 193504.

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J. Panda, K. Jena, R. Swain, T. R. Lenka. Modeling on oxide dependent 2DEG sheet charge density and threshold voltage in AlGaN/GaN MOSHEMT[J]. J. Semicond., 2016, 37(4): 044003. doi: 10.1088/1674-4926/37/4/044003.

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Manuscript received: 04 July 2015 Manuscript revised: Online: Published: 01 April 2016

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