Ultrafine/High-speed electron devices based on buried nano-metal-wires in compound semiconductors

我们的研究包括以下两个学期。采用埋地纳米金属线作为栅极提取电子的发射极结构制备了埋地纳米金属线提取电子离子的热电子晶体管。在直流特性中，饱和I-V特性得到了证实。为了抑制从发射极到栅极的电流注入，发明了一种新的结构（已申请专利），将发射极电流与栅极电流之比提高到几十倍。根据观察到的直流特性估计跨导为10 mS。为了减少电子的散射，确定了InP本征层的纯度。结果表明，AlInAs/InP HEMT结构在77K下的电子迁移率为110,000 cm^2/Vs，当掺杂si层被消除时，在77K下的电子迁移率为220,000 cm^2/Vs。据我们所知，这些在77K的机动性是世界纪录。从而证实了我们材料的高纯度。埋地纳米金属线集电极结构。通过晶体生长的研究，我们发现导线上过层的厚度随导线的数量而变化。由于晶体生长的失败是由于这种现象，我们制造的结构只有一根导线作为集电极，细化晶体生长条件。因此，我们用一根纳米金属线作为集电极制备了HBT。在本设备中，发射器面积为0.1μm×0.5μm。据我们所知，这个面积在异质结双极晶体管中是最小的。最小的总集电极电容也被确认。作为接触电阻，通过改变电极材料（从钛到钯），发射极接触电阻率从3x10^<-6>Wcm^2降低到1x10^<-6>Wcm^2，基极接触电阻率从2.5x10^<-6>Wcm^2降低到3x10^<-7>Wcm^2。这种减小与小集电极电容相结合对于获得良好的微波性能是非常重要的。

Our researches consisted of following two terms.1.Emitter structure for extraction of electrons by buried nano-metal-wires as gateWe fabricated hot electron transistors with buried nano-metal -wires to extract ion of electron. In DC characteristics, saturated I-V characteristics was confirmed.To suppress current injection from emitter to gate, new structure was invented (patent applied for) and ratio between emitter current vs. gate current was enhanced to several tens. Estimated transconductance was 10 mS from obserbed DC charactarisrtics.To reduce scattering of electron, purity of InP intrinsic layer was confirmed. As a result, electron mobility of 110,000 cm^2/Vs at 77 K was confirmed in AlInAs/InP HEMT structure, When Si-doped layer was eliminated, electron mobility of 220,000 cm^2/Vs at 77K was confirmed. To our knowledge, these mobility at 77K was world records. Thus high purity of our materials was confirmed.2.Collector structure by buried nano-metal-wire.Through study through crystal growth, we found that thickness of over layer on wires was changed by the number of wires. Because failure of crystal growth was due to this phenomena, we fabricated the structure with only one wire as a collector with refinement of crystal growth conditions. As a result, we fabricated HBT with one nano^metal wire as collector. In this device, the emitter area was 0.1μm×0.5μm. To our knowledge, this area was smallest as heterojunction bipolar transistors. Smallest total collector capacitance was also confirmed.As a contact resistance, emitter contact resistivity was reduced from 3x10^<-6>Wcm^2 to 1x10^<-6>Wcm^2 and base contact resistivity was reduced from 2.5x10^<-6>Wcm^2 to 3x10^<-7>Wcm^2 by change of electrode material (from titanium to pallsdium). This reduction combined with small collector capacitance is very important to obtain good microwave performance.