Avalanche Breakdown Luminescence of InGaN/AlGaN/GaN Heterostructures
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Internet Journal o f
Nitride S emiconductor Research
Volume 2, Article 11
Avalanche Breakdown Luminescence of InGaN/AlGaN/GaN Heterostructures F. Manyakhin, A. Kovalev Moscow Institute of Steel and Alloys V. E. Kudryashov, A. N. Turkin, A. E. Yunovich Moscow State Lomonosov University This article was received on June 5, 1997 and accepted on July 10, 1997.
Abstract Luminescence spectra of InGaN/AlGaN/GaN p-n-heterostructures were studied at reverse bias sufficient for impact ionization. There is a high electric field in the active InGaN-layer, and the tunnel component of the current dominates at the low reverse bias. Avalanche breakdown begins at |Vth|> 8◊10 V, i.e. ≈3 Eg/e. Radiation spectra have a short wavelength edge 3.40 eV, and maxima in the range 2.60◊2.80 eV corresponding to the injection spectra. Mechanisms of the hot plasma recombination in p-n-heterojunctions are discussed.
1. Introduction Injection luminescence spectra of superbright blue and green light-emitting diodes (LEDs) based on InGaN/AlGaN/GaN heterostructures were studied in [1] [2] [3] [4] [5]. It was interesting to study the breakdown luminescence in the same structures hoping to receive some additional information on the parameters which influence on the properties of effective LEDs. Avalanche breakdown luminescence in GaN was studied previously in cases of i-n- and MIS - diodes [6] [7] [8] [9]. It was shown that at reverse bias, electrons are tunneling from metal to the n-side of the junction and at sufficiently high voltage cause impact ionization and avalanche breakdown. There is a high electric field in the active layer of the blue InGaN/AlGaN/GaN LEDs as it was concluded from the spectral and capacitance measurements [3] [4] [5]. The high doping of the p-side and a thin active layer distinguish these LEDs from the previous [6] [7] [8] [9] [10] ones. In this paper we describe breakdown luminescence spectra of blue LEDs and analyze electrical and luminescence properties of InGaN/AlGaN/GaN structures at reverse bias.
2. Experimental results We have studied the LEDs based on the InGaN/AlGaN/GaN structures with a thin layer - quantum well InGaN - described in [1] [2]. Blue LEDs with known parameters of the injection luminescence spectra [2] [3] [4] were chosen for measurements. Reverse current-voltage and capacitance-voltage curves of a blue diode (N 3) are shown in Figure 1 and Figure 2. The main part of the curves at |V|< 10 V can be approximated by two exponents: J ~ exp(e| V /EJ ), ih
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Downloaded from https://www.cambridge.org/core. The University of Iowa, on 23 Nov 2019 at 09:31:29, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/S109257830000137X
with a parameter EJ = 0.86◊0.90 eV changing near |V| = 5◊6 V. The change in the slopes of derivatives dV/d(lnJ) is shown in Figure 1. The reverse current-voltage characteristics of the green LEDs differed from the blue ones (see Figure 3), according to lowe
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