Photoluminescence Study of Plasma-Induced Damage of GaInN Single Quantum Well

Abstract

Plasma-induced damage (PID) due to Cl2/SiCl4/Ar plasma etching of the GaN capping layer (CAP)/GaInN single quantum well (SQW)/GaN structure was investigated by conventional photoluminescence (PL), transmission electron microscopy (TEM), and time-resolved and temperature-dependent photoluminescence (TRPL). SQW PL intensity remained constant initially, although plasma etching of the CAP layer proceeded, but when the etching thickness reached a certain amount (∼60 nm above the SQW), PL intensity started to decrease sharply. On the other hand, TEM observations show that the physical damage (structural damage) was limited to the topmost surface region. These findings can be explained by the results of TRPL studies, which revealed that there exist two different causes of PID. One is an increase in the number of nonradiative recombination centers, which mainly affects the PL intensity. The other is an increase in the quantum level fluctuation owing mainly to physical damage.

Low damage dry etch for III-nitride light emitters

“…The noise floor of the data is determined by a sample in which the QWs have been completely etched through; residual PL is from the <5% unetched area that was used for etch depth measurements. These results match well with a dry etch study conducted by Sony [9]. They also observed a sharp decrease in PL intensity after etching within 60 nm of their single QW active region.…”

“…Sub-surface dry etch damage in GaN is well known, with many approaches to heal this damage and recover electrical characteristics [6][7][8][9][10][11][12][13]. Damaged active regions can also be partially recovered with high temperature (900 °C) anneals [13], but avoiding any etch damage altogether is preferred.…”

Suppression of plasma-induced damage on GaN etched by a Cl2plasma at high temperatures

“…Relative to photon-induced damage, the ion-induced damage was significantly suppressed at 500 °C and thereby the photon-induced damage was predominant. Since photons could not induce damage at room temperature, as reported by Minami et al 16) and Izumi et al, 24) the synergistic work of photon and thermal annealing led to the enhancement in the deterioration of PL. This could be a result of degraded crystal quality due to thermal dissociation, because the samples were grown by HVPE with a high threading dislocation (1 × 10 9 =cm 2 ).…”

Temperature dependence on plasma-induced damage and chemical reactions in GaN etching processes using chlorine plasma

“…All the effects of ions, radicals, and photons were separately analyzed by the pallet for plasma evaluation (PAPE) method. [27][28][29] A GaN sample was covered with a MgF 2 window or a Si wafer. 26) The sample covered with the MgF 2 window, which transmitted light with wavelengths longer than 115 nm, was used to evaluate separately the effect of photons from that of plasma.…”