Microwave Determination of Quantum-Well Capture and Escape Time in Light-Emitting Transistors

Abstract

We report the determination of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{In}_{0.20}\hbox{Ga}_{0.80}\hbox{As}$ </tex></formula> quantum-well (QW) capture and escape time by utilizing electrical microwave measurement on an InGaP/GaAs light-emitting transistor (LET) platform. The emitter-to-collector transit times <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\tau_{\rm ec}$</tex></formula> of the LET and the heterojunction bipolar transistor (HBT) are measured and extracted under the same bias condition ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V_{ \rm bc} = \hbox{0}\ \hbox{V}$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$J_{c} = \hbox{22.6}\ \hbox{kA}/\hbox{cm}^{2}$</tex></formula> ). Small-signal model analysis shows that the LET exhibits a larger base transit time <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\tau_{t}$</tex></formula> of 25 ps compared with 5 ps of the HBT. The difference, i.e., 20 ps, hence is attributed to the carrier capturing/escaping processes caused by the QWs embedded in the base region of the LET.