自对准栅型谐振隧穿晶体管试制

Fabrication of a resonant tunneling transistor with self-aligned gate

针对谐振隧穿二极管（RTD）在通用电路应用中的局限性,提出并设计了自对准栅型谐振隧穿晶体管结构,进行了材料的分子束外延,采用传统湿法腐蚀、金属剥离、台面隔离和空气桥互连工艺,初步研制出具有较明显栅控能力的谐振隧穿晶体管（RTT）单管,其峰值电流密度高达80.8kA/cm^2,峰谷电流比为3.6,负阻阻值在20Ω左右。研究还发现,器件的峰值电流随栅压增大而减小,谷值电流随栅压增大而增大,而且出现零点分离。这些现象与栅的纵向位置控制不当有关,可以通过减小栅间发射极宽度,缩短栅与势垒层距离,和减小发射层掺杂浓度得到改善。

In view of the application limits of resonant tunneling diodes in common circuits, the study put forward and designed a novel resonant tunneling transistor structure with a self-aligned gate. The material was grown by molecular beam epitaxy. The device with better gate control characteristic was fabricated adopting wet chemical etch, metal lift-off, mesa isolation and air bridge technology. Its peak current density was 80.8kA/cm^2, the ratio of peak to valley current was 3. 6 and the negative differential resistance value was about 20Ω. The study also found that the peak current decreased and the valley current increased with the increasing of gate voltage, and zero points separated. All the above phenomena were caused by improper longitudinal gate site. They can be improved by shortening emitter＇ s width, reducing the distance between gate and barrier layer or decreasing the doping concentration of emitter layer.