Bandgap and Strain Engineering in SiGeC Heterojunction Bipolar Transistors

Abstract

The incorporation of C into Si1-x Ge x alloys contributes to enlarging the critical layer thickness and to improving the thermal budget. It also realizes a narrower bandgap with compensated strain. These effects would introduce good performance at high frequency in the devices. We fabricate heterojunction bipolar transistors (HBTs) with an Si1-x-y Ge x C y base layer using ultrahigh-vacuum chemical vapor deposition (UHV-CVD) technology. The bandgaps of Si1-x-y Ge x C y base layers are measured by the evaluation of the collector current dependence on temperature. The strain of the pseudomorphic Si1-x-y Ge x C y layer is also extracted by an analysis of the X-ray diffraction spectra. Good flexibility of Si1-x-y Ge x C y alloy is shown for the bandgap and strain engineering. The devices using the excellent characteristics of Si1-x-y Ge x C y alloy have numerous applications for wireless telecommunications.

First- and second-order electrical modelling and experiment on very high speed SiGeC heterojunction bipolar transistors

“…The interfaces between different materials must be properly described. The band-gap energy is dependent not only on the Ge mole fraction x in the base and the fraction y of carbon but also on the amount of strain in the base layer, which in turn depends on the type of substrate used; then the SigeC bandgap, depending on the Sige bandgap, will be assumed to vary according to the equation below [12]; in our simulation, we used essentially 20% of Ge and 0.75% of carbon concentration:…”

Strain Engineering in Monolayer Materials Using Patterned Adatom Adsorption

“…1 One example is strained silicon technology, which has been widely employed to enhance electron or hole mobility in metal-oxide-semiconductor field-effect transistors (MOSFETs). 2−4 One might expect strain engineering to be at least as relevant in monolayer materials because they can sustain large strains unachievable in bulk materials.…”