Degradation of InGaN/GaN laser diodes investigated by micro-cathodoluminescence and micro-photoluminescence

Abstract

We present an investigation of the degradation of InGaN/GaN laser diodes grown on a GaN substrate. The results indicate that: (i) Ageing induces a significant increase in the threshold current (Ith) of the lasers, which is attributed to an increase in non-radiative recombination; (ii) Ith increase is correlated to a decrease in the micro-cathodoluminescence signal measured (after the removal of the top metallization) in the region under the ridge; (iii) micro-photoluminescence measurements indicate that constant current stress increases non-radiative recombination within the quantum wells (and not only within the barriers), and induces an increase in the emission wavelength of the degraded regio

Simultaneous specimen current and time-dependent cathodoluminescence measurements on gallium nitride

“…However, TDs have also been correlated with enhanced diffusion processes to promote device degradation. 3 The abundance of V Ga has prompted the tentative assignment of a number of radiative and non-radiative luminescence in GaN. Indeed, V Ga were originally correlated with the origin of deep level (DL) yellow emission, 10 now attributed to C N complexes through density functional theory calculations.…”

Integration of an opto-chemical detector based on group III-nitride nanowire heterostructures

“…4 a conceptual layout of the miniaturized sensor system with a size of approximately 30 mm × 60 mm × 30 mm satisfying both requirements is shown. The linear polarized excitation radiation at 405 nm is emitted by a laser diode (output facet size 2.0 μm × 0.4 μm) with a divergence of 10°( FWHM) in slow axis and 22°(FWHM) in fast axis [6]. With two optical surfaces the light is shaped to an aberration-minimized focus at the gas-sensitive nanowires at the top of the system.…”

Electric-field-induced band bending on GaN: in situ effects of electron beam irradiation on time-dependent cathodoluminescence

“…Furthermore, Nykänen confirmed the activation of Ga vacancy defects (V Ga ) upon low-energy electron beam irradiation conditions that emulate device operation [13,14]. The regained interest in CL analysis [1,15], through former aims to address emission lifetimes [16] and the latter to unveil a plethora of physical phenomena, often providing insight into device operation and failure [12][13][14]. The underlying phenomena are the result of complex interplay between carriers and extended defects [8,13,14,17], as well as surface states nucleating upon device operation [1,6,17] in addition to V Ga activation [13,14].…”

“…Understanding this phenomenology is a doorway to infer device operation and subsequent degradation, providing deep insights into unresolved defect dynamics within GaN in particular [12]. Meneghini et al attributed the degraded operation of indium gallium nitride/gallium nitride (InGaN/GaN) laser diodes to increased nonrecombination efficiency upon aging.…”

“…Experiments also investigated the effects of unintended humidity adsorption on near band edge CL (NBE-CL) intensity and on SE yield, given the prior-established importance of surface states in GaN [18]. Understanding of electric-field effects on GaN, inclusive of water adsorption effects [20], will offer insights into optoelectronics aging and device performance [12,13], as well as identify opportunities toward radiation-hard electronics and microsystems in harsh environments [21,22].…”