Enhancement-Mode GaN-Based High-Electron Mobility Transistors on the Si Substrate With a P-Type GaN Cap Layer

An enhancement-mode (E-mode) high-electron mobility transistor (HEMT) was demonstrated by inserting a p-type GaN layer underneath the gate electrode. The effects of process flows and device structures on the electrical properties are investigated in this paper. We demonstrated a threshold voltage (Vth) of 4.3 V by adjusting the built-in voltage of the diode formed between the p-GaN and channel by the alloy temperature. Next, we found the existence of parallel conduction paths of the p-GaN layer and 2-D electron gas (2DEG) channel in such a HEMT structure. By removing p-GaN above the gate-source and gate-drain regions, current conduction migrates from p-GaN to 2DEG channel. The process window of the p-GaN residual thickness to ensure a steady forward current-voltage operation was estimated to be 10±5 nm in our case. Finally, with the p-GaN underneath the gate contact to deplete surface leakage current, an E-mode HEMT with a breakdown voltage (VBD) of 1630 V is achieved.

[1]  S. Shen,et al.  Threshold Voltage Control of Recessed-Gate III-N HFETs Using an Electrode-less Wet Etching Technique , 2011 .

[2]  H. Miyamoto,et al.  A normally-off GaN FET with high threshold voltage uniformity using a novel piezo neutralization technique , 2009, 2009 IEEE International Electron Devices Meeting (IEDM).

[3]  Lester F. Eastman,et al.  Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures , 1999 .

[4]  M. Kiyama,et al.  High-breakdown-voltage pn-junction diodes on GaN substrates , 2007 .

[5]  James S. Speck,et al.  Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistors , 2000 .

[6]  Yugang Zhou,et al.  High-performance enhancement-mode AlGaN/GaN HEMTs using fluoride-based plasma treatment , 2005, IEEE Electron Device Letters.

[7]  J. Wurfl,et al.  Normally-off high-voltage p-GaN gate GaN HFET with carbon-doped buffer , 2011, 2011 IEEE 23rd International Symposium on Power Semiconductor Devices and ICs.

[8]  K.J. Chen,et al.  Monolithic integration of lateral field-effect rectifier with normally-off HEMT for GaN-on-Si switch-mode power supply converters , 2008, 2008 IEEE International Electron Devices Meeting.

[9]  T. Oka,et al.  AlGaN/GaN Recessed MIS-Gate HFET With High-Threshold-Voltage Normally-Off Operation for Power Electronics Applications , 2008, IEEE Electron Device Letters.

[10]  Kinam Kim,et al.  1.6kV, 2.9 mΩ cm2 normally-off p-GaN HEMT device , 2012, 2012 24th International Symposium on Power Semiconductor Devices and ICs.

[11]  R. Dimitrov,et al.  Two dimensional electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN/GaN heterostructures , 2000 .

[12]  Mitsuaki Shimizu,et al.  Effect of hole injection in AlGaN/GaN HEMT with GIT structure by numerical simulation , 2012 .

[13]  T. Egawa,et al.  Breakdown Enhancement of AlGaN/GaN HEMTs on 4-in Silicon by Improving the GaN Quality on Thick Buffer Layers , 2009, IEEE Electron Device Letters.

[14]  C. H. Lee,et al.  Inversion-channel GaN MOSFET using atomic-layer-deposited Al2O3 as gate dielectric , 2009, 2009 International Symposium on VLSI Technology, Systems, and Applications.

[15]  T. Egawa,et al.  Buffer Thickness Contribution to Suppress Vertical Leakage Current With High Breakdown Field (2.3 MV/cm) for GaN on Si , 2011, IEEE Electron Device Letters.

[16]  J. Wurfl,et al.  Punchthrough-Voltage Enhancement of AlGaN/GaN HEMTs Using AlGaN Double-Heterojunction Confinement , 2008, IEEE Transactions on Electron Devices.

[17]  H. Ishida,et al.  Gate Injection Transistor (GIT)—A Normally-Off AlGaN/GaN Power Transistor Using Conductivity Modulation , 2007, IEEE Transactions on Electron Devices.

[18]  Eldad Bahat Treidel,et al.  Normally-off AlGaN/GaN HFET with p-type GaN gate and AlGaN buffer , 2010, 2010 6th International Conference on Integrated Power Electronics Systems.

[19]  J. M. Hong,et al.  Inversion-channel GaN metal-oxide-semiconductor field-effect transistor with atomic-layer-deposited Al2O3 as gate dielectric , 2008 .

[20]  T. Tanaka,et al.  Nonpolar AlGaN/GaN HFETs with a normally off operation , 2012 .

[21]  T. Egawa,et al.  MOCVD grown normally-OFF type AlGaN/GaN HEMTs on 4 inch Si using p-InGaN cap layer with high breakdown , 2010, 68th Device Research Conference.

[22]  J. Wurfl,et al.  Normally-off AlGaN/GaN HFET with p-type Ga Gate and AlGaN buffer , 2010, 2010 22nd International Symposium on Power Semiconductor Devices & IC's (ISPSD).

[23]  Hideki Hasegawa,et al.  Al2O3 Insulated-Gate Structure for AlGaN/GaN Heterostructure Field Effect Transistors Having Thin AlGaN Barrier Layers , 2004 .