$\hbox{In}_{0.46}\hbox{Ga}_{0.54}\hbox{P}_{0.98} \hbox{Sb}_{0.02}/\hbox{GaAs}$: Its Band Offset and Application to Heterojunction Bipolar Transistor

Abstract

We report on the band alignment of In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.46</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.54</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.98</sub> Sb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.02</sub> /GaAs and the dc characteristics of In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.46</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.54</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.98</sub> Sb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.02</sub> /GaAs heterojunction bipolar transistors (HBTs). By comparing the forward and reverse Gummel plot, we found a potential spike existing at the InGaPSb/GaAs interface. Through a flatband extrapolation from the currents of the forward and reverse Gummel plot and the energy gap determined from photoluminescence, we concluded that In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.46</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.54</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.98</sub> Sb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.02</sub> /GaAs is in a type-I band alignment. The conduction-band offset and valence-band offset are 0.12 and 0.35 eV, respectively. As a result of the type-I band alignment, the InGaPSb/GaAs HBTs showed a more significant thermal degradation of the current gain than the control InGaP/GaAs HBT. The thermal behavior is beneficial to ruggedness.