Room-Temperature Resonant Tunneling Diode with High-Ge-Fraction Strained Si1-xGex 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 Si1-xGex/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 Si2H6 reaction at a lower temperature of 400oC instead of SiH4 reaction at 500oC after the Si0.42Ge0.58 growth. NDC characteristics show that difference between peak and valley currents is effectively enhanced at 11-295K by using Si2H6 at 400oC, compared with that using SiH4 at 500oC. 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