Temperature-Dependent Characteristics of a GaN/InGaN/ZnO Heterojunction Bipolar Transistor

Abstract

This work presents dc characteristics (gain and leakage current) of a GaN/InGaN/ZnO npn collector-up heterojunction bipolar transistor (HBT) measured at 300, 200, and 100 K. The GaN-based epilayers of HBT were grown by metallorganic chemical vapor deposition, and the n-ZnO film was then deposited on top of p-InGaN by sputtering. X-ray diffraction analysis demonstrates that annealing at 600°C for 60 s in ambient normalN2 improved the quality of the ZnO film. Moreover, this study shows that the current gains (β) from the Gummel plot increased as the temperature decreased because the leakage current of the collector current (InormalC) is not a strong function of temperature. However, gains (GCE) from the measured common-emitter current–voltage characteristics increased slightly as the temperature decreased due to a reduction in the recombination current coupled with lower injection efficiency. These preliminary results show the potential of fabricating GaN/InGaN/ZnO HBTs without dry etching to reach the p-GaN layer, as required in the emitter-up geometry.

Computation of Electronic Energy Band Diagrams for Piezotronic Semiconductor and Electrochemical Systems

“…[1][2][3][4][5][6][7][8] These effects can be further modified by introducing dipole fields such as the case when poled ferroelectrics and strained piezoelectric materials are used, i.e., the piezotronics. Through differences in charge densities, electrical permittivities, electrochemical potentials, and electronic structures, the flow of electrical current may be impeded, made exquisitely sensitive to mechanical, thermal, electrical, and chemical stimuli, and even be used to drive chemical transformations.…”

“…At the core of an electronic device's functionality and tunability is the coupling of dissimilar materials. Through differences in charge densities, electrical permittivities, electrochemical potentials, and electronic structures, the flow of electrical current may be impeded, made exquisitely sensitive to mechanical, thermal, electrical, and chemical stimuli, and even be used to drive chemical transformations . These effects can be further modified by introducing dipole fields such as the case when poled ferroelectrics and strained piezoelectric materials are used, i.e., the piezotronics.…”