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Reliability improvement of GaN-based devices by controlling defects and interfaces

通过控制缺陷和界面提高GaN基器件的可靠性

基本信息

批准号：
17360133
负责人：
HASHIZUME Tamotsu
金额：
$ 9.86万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360133/
关键词：
GaN AIGaN DLTS deep level carbon diffusion surface control Schottky interface HEMT プラズマ処理窒素空孔欠陥酸素不純物漏れ電流 MIS構造

项目摘要

The purpose of the research is to improve the stability of the GaN-based devices by controlling defects and interfaces. We have characterized electronic states of defects and impurities in GaN and A1GaN, as well as their correlation with degradation phenomena in various kinds of devices, such as the current collapse, the gate leakage current, electric breakdown, etc.1)We performed deep level transient spectroscopy (DLTS) measurements on the Schottky contacts fabricated on the Al_0.26Ga_0.74N surfaces, and detected a deep electron trap with an activation energy of 0.9 eV and a density higher than 1 x 10^16 cm^<-3>.2)We developed a diffusion process for carbon doping into GaN, using a CN_x/SiN_x bilayer. The C-rich CN_x layer was deposited on n-GaN while we used stoichiometric Si3N4 as a capping layer. The secondary ion mass spectroscopy (SIMS) result indicated the C diffusion into n-GaN in concentration higher than 1x 1018 cm-3 after an annealing at 1000 ℃ for 2hrs.3)We have developed a … More novel surface process for controlling electronic states at the AlGaN surfaces, The process consists of the deposition of ultrathin Al layer on the A1GaN surfaces and the in-situ UHV anneal at 700 ℃, resulting in the gettering of oxygen donors from the A1GaN surface into the Al layer. After the process, we observed pronounced reduction of the leakage current and the temperature-dependent current-voltage characteristics in the Ni/AlGaN interfaces.4)By applying the high-temperature or UV-assisted capacitance-voltage measurements on the insulator-GaN interfaces, we could firstly observed the response from the interface states near midgap of GaN. We also found that the ultrathin Al-oxide layer on the GaN surface was very effective in controlling interface states.5)We investigated the operation stability of the A1GaN/GaN high-mobility transistors (HEMTs) after applying the off-state stress at high temperatures. The devices without the unltrathin-Al based surface control process showed significant degradation in DC characteristics after the stress, mainly due to the increase in the drain conductance. On the other hand, no change in the the DC characteristics were observed in HEMTs with the surface process after the stress. Less

研究的目的是通过控制缺陷和接口来提高氮化镓器件的稳定性。我们表征了GaN和A1GaN中缺陷和杂质的电子态，以及它们与各种器件中降解现象（如电流崩溃、栅漏电流、电击穿等）的相关性。1)我们对在al_0 .26 ga0 .74 n表面上制备的肖特基触点进行了深能级瞬态光谱（DLTS）测量。发现了一个活化能为0.9 eV，密度大于1 × 10^16 cm^<-3>的深电子阱。2)我们开发了一种利用CN_x/SiN_x双分子层将碳掺杂到GaN中的扩散工艺。富碳CN_x层沉积在n-GaN上，而我们使用化学计量的Si3N4作为覆盖层。次级离子质谱（SIMS）结果表明，在1000℃退火2h后，C扩散到浓度大于1 × 1018 cm-3的n-GaN中。3)我们开发了一种更新颖的控制AlGaN表面电子态的表面工艺，该工艺包括在A1GaN表面沉积超薄Al层，并在700℃下进行现场特高压退火，使供氧体从A1GaN表面进入Al层。在此过程之后，我们观察到Ni/AlGaN界面的泄漏电流和温度相关的电流-电压特性明显降低。4)通过对绝缘体-GaN界面进行高温或紫外辅助的电容电压测量，我们可以首次观察到GaN中隙附近界面状态的响应。我们还发现氮化镓表面的超薄氧化铝层对控制界面状态非常有效。5)研究了高温下施加非稳态应力后A1GaN/GaN高迁移率晶体管（hemt）的工作稳定性。未采用超薄铝基表面控制工艺的器件在应力作用后直流特性明显下降，主要是由于漏极电导的增加。另一方面，应力处理后hemt的直流特性没有发生变化。少