Room-temperature resonant tunneling diode with high-Ge-fraction strained Si_1-xGe_x and nanometer-order ultrathin Si

For the purpose of heterointegration of Si-based group IV semiconductor quantum effect devices into Si large-scale integrated circuit, formation of atomically flat heterointerfaces in quantum heterostructure by lowering Si barrier growth temperature was investigated in order to improve negative differential conductance (NDC) characteristics of high-Ge-fraction strained Si_1-xGe_x/Si hole resonant tunneling diode. It was found that roughness generation at heterointerfaces is drastically suppressed by utilizing, Si barriers with nanometer order thickness deposited using Si ₂H₆ reaction at a lower temperature of 400°C instead of SiH₄ reaction at 500°C after the Si_0.42Ge _0.58 growth. NDC characteristics show that difference between peak and valley currents is effectively enhanced at 11-295K by using Si ₂H₆ at 400°C, compared with that using SiH₄ at 500°C. Thermionic-emission dominant characteristics at higher temperatures above 100 K indicates a possibility that introduction of larger barrier height (i.e., larger band discontinuity) enhances the NDC at room temperature by suppression of thermionic-emission current.