Atomically Controlled Formation of Strained Si1-xGex/Si Quantum Heterostructure for Room-Temperature Resonant Tunneling Diode

Abstract

Atomically controlled formation of strained Si1-xGex/Si quantum heterostructure was investigated in order to improve negative differential conductance (NDC) characteristics of high-Ge-fraction strained Si1-xGex/Si hole resonant tunneling diode with nanometer-order thick strained Si1-xGex and unstrained Si layers. Recently, especially to suppress the roughness generation at heterointerfaces for higher Ge fraction, Si barriers were deposited using Si2H6 reaction at a lower temperature of 400 oC instead of SiH4 reaction at 500 oC after the Si0.42Ge0.58 growth. NDC characteristics show that difference between peak and valley currents is effectively enhanced at 11-295 K by using Si2H6 at 400 oC, compared with that using SiH4 at 500 oC. Thermionic-emission dominant characteristics suggests a possibility that introduction of larger barrier height enhances the NDC at room temperature by suppression of thermionic-emission current. In this paper, based on our results, advanced epitaxial growth process of RTDs with atomically controlled Si/strained Si1-xGex heterostructures on Si(100) are reviewed.