Ultralow Interface Recombination Velocity (∼1 cm/s) at CdTe/MgxCd ${}_{1\hbox{-}}$xTe Heterointerface

Abstract

The interface recombination velocity (IRV) at the interfaces in CdTe/Mg <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_x</i> Cd <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${}_{1\hbox{-}}$</tex-math></inline-formula> <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_x</i> Te double heterostructures (DHs) is studied using time-resolved photoluminescence. It is found that both thermionic emission and tunneling effects can cause photogenerated carrier loss over or through the Mg <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_x </i> Cd <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${}_{1\hbox{-}}$</tex-math></inline-formula> <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_x </i> Te barriers, either due to the low barrier potential or the thin barrier thickness. Thus, carrier lifetime measurements reveal only an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">effective</i> IRV. The thermionic emission induced interface recombination can be distinguished by conducting temperature-dependent carrier lifetime measurements, and the tunneling induced IRV can be quantified by comparing samples with different barrier thicknesses. When both thermionic emission and tunneling effects are suppressed or even eliminated, the actual IRV (due to the recombination at the DH interface trap states) is measured to be ∼1 cm/s, with a very long carrier lifetime of 3.6 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> s achieved in the DHs.