Space–Charge-Limited Photocurrent as a Possible Cause for Low Power Conversion Efficiency in GaInN/GaN-Based Optoelectronic Semiconductors

Abstract

This study attempts to understand the cause of low power conversion efficiency (PCE) in III-nitride optoelectronic semiconductors under optical operation. For this purpose, a GaInN/GaN heterojunction semiconductor is fabricated, and the photoexcited current–voltage (PEJV) curves are carefully measured depending on the optical excitation power and temperature. The results show unexpected excitation power- and temperature-dependent behaviors, that is, the PCE decreases with increasing excitation power and increases with increasing temperature. To understand this, the space–charge-limited photocurrent (JPh,SCL) theory (also referred to as Goodman and Rose theory) is employed, where the accumulated charge carriers in the active layer play a significant role. The conduction of JPh,SCL is ascertained by analyzing the PEJV curves. The conduction of JPh,SCL is investigated as a possible cause of the low PCE, revealing that the conduction of JPh,SCL could limit the high-power operation of the device. © 2024 The Authors. physica status solidi (a) applications and materials science published by Wiley-VCH GmbH.