Research for ultra-fast operation of InP HBT by ballistic transportation in collector

本文的研究结果如下：用蒙特卡罗模拟方法估算了集热器中的电子速度。在集电极厚度为10 0 nm的异质结双极晶体管中，电子速度在最初的40 nm处大于4×10 7 cm/S，但在最后的2 0 nm处速度小于2×10 7 cm/S。在基区厚度为25 nm的情况下，估计截止频率约为630 GHz，因此我们提出了用本征半导体热电子晶体管作为弹道传输的传播区，以及用绝缘栅控制高驱动能力的热离子异质发射器。当集电极电流密度大于1000kA/cm2时，集电极内电子速度大于7×107 cm/S，截止频率大于1 THz。采用0.1um宽埋线的异质结双极晶体管的总集电极电容为0.6fF。据我们所知，这是最小的电容。然而，来自导线一侧的电子通量限制了进一步的改进。因此，我们提出了基极接触区SiO_2丝异质结双极晶体管。200 nm厚的导线被埋在具有平坦异质界面的异质结双极晶体管结构中。在有SiO_2丝的晶体管中，直流测量没有观察到严重的退化。制作了具有绝缘栅和热离子异质发射器的热电子晶体管。证实了栅极偏置控制的栅极和集电极电流的良好隔离。

Obtained results in this study are as follows :Electron velocity in the collector was estimated by Monte Carlo simulation. In the heterojunction bipolar transistor with 100 nm thick collector, electron velocity is over 4x10^7cm/s at first 40 nm, but the velocity is less than 2x10^7cm/s at final 20 nm. With base thickness of 25 nm, estimated cutoff frequency is about 630 GHz.Thus we propose hot electron transistors with intrinsic semiconductor as propagation region for ballistic transportation and thermionic hetero-launcher for high drivability controlled by insulated gate. Electron speed in the collector is over 7x10^7cm/s and cutoff frequency over 1 THz is estimated when collector current density is over 1000 kA/cm^2.Heterojunction bipolar transistors with 0.1um wide buried metal wires showed 0.6 fF as total collector capacitance. To our knowledge, this is the smallest capacitance. However, electron flux from side of the wire limits further improvement. Thus we proposed heterojunction bipolar transistors with SiO_2 wire under base contact region. 200-nm-thick wires were buried in heterojunction bipolar transistor structure with flat hetero-interface. In the transistors with SiO_2 wire, no serious degradation was observed in DC measurements. Hot electron transistors with insulated gate and thermionic hetero-launcher were fabricated. Good isolation of gate and collector current control by gate bias were confirmed.