论文信息 - An AlGaN/GaN HEMT with a reduced surface electric field and an improved breakdown voltage

An AlGaN/GaN HEMT with a reduced surface electric field and an improved breakdown voltage

A reduced surface electric field in an AlGaN/GaN high electron mobility transistor (HEMT) is investigated by employing a localized Mg-doped layer under the two-dimensional electron gas (2-DEG) channel as an electric field shaping layer. The electric field strength around the gate edge is effectively relieved and the surface electric field is distributed evenly as compared with those of HEMTs with conventional source-connected field plate and double field plate structures with the same device physical dimensions. Compared with the HEMTs with conventional source-connected field plates and double field plates, the HEMT with a Mg-doped layer also shows that the breakdown location shifts from the surface of the gate edge to the bulk Mg-doped layer edge. By optimizing both the length of Mg-doped layer, Lm, and the doping concentration, a 5.5 times and 3 times the reduction in the peak electric field near the drain side gate edge is observed as compared with those of the HEMTs with source-connected field plate structure and double field plate structure, respectively. In a device with VGS = −5 V, Lm = 1.5 μm, a peak Mg doping concentration of 8×1017 cm−3 and a drift region length of 10 μm, the breakdown voltage is observed to increase from 560 V in a conventional device without field plate structure to over 900 V without any area overhead penalty.

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

[2] J. Yang,et al. Reduced gate leakage current in AlGaN/GaN HEMT by oxygen passivation of AlGaN surface , 2008 .

[3] C. Xu,et al. The Leakage Current of the Schottky Contact on the Mesa Edge of AlGaN/GaN Heterostructure , 2007, IEEE Electron Device Letters.

[4] Ichiro Omura,et al. High breakdown voltage AlGaN-GaN power-HEMT design and high current density switching behavior , 2003 .

[5] A. G. Chynoweth,et al. Ionization Rates for Electrons and Holes in Silicon , 1958 .

[6] Y. Okamoto,et al. 10-W/mm AlGaN-GaN HFET with a field modulating plate , 2003, IEEE Electron Device Letters.

[7] J. Zolper,et al. Redistribution of implanted dopants in GaN , 1999 .

[8] Y. Aoyagi,et al. Remarkable breakdown voltage enhancement in AlGaN channel high electron mobility transistors , 2008 .

[9] Yu Fu-qiang,et al. Calculations of two dimensional electron gas distributions in AlGaN/GaN material system , 2008 .

[10] M. Kelly,et al. Radiation damage annealing (thermal and laser) in Mg implanted GaN , 2005 .

[11] Jun-Dar Hwang,et al. Activation of Mg-doped P-GaN by using two-step annealing , 2007 .