MIJ-NSR Vol. 3, Art. 44, A. E. Yunovich et al.

The Emission Properties of Light Emitting Diodes using InGaN/AlGaN/GaN Multiple Quantum Wells

A. E. Yunovich, V. E. Kudryashov, A. N. Turkin
M.V.Lomonosov Moscow State University

A. Kovalev, F. Manyakhin
Moscow Institute of Steel and Alloys

This article was received on Sunday, June 21, 1998 and accepted on Friday, October 23, 1998.

Abstract

Luminescence spectra of Light Emitting Diodes (LEDs) with Multiple Quantum Wells (MQWs) were studied at currents J = 0.15 µA - 150 mA. A high quantum efficiency at low J is caused by a low probability of the tunnel current J (which is maximum at J_m

0.5-1.0 mA). J(V) curves were measured in the range J= 10^-12-10^-1 A; at J > 10^-3A they may be approximated by a sum of four parts: V=

_k+ mkT·[ln(J/J₀)+(J/J₁)^0.5] + J·R_s. The part V ~ (J/J₁)^0.5is the evidence of a double-injection into i-layers near MQWs. Their presence is confirmed by capacitance measurements. An overflow of carriers through the MQW causes a lower quantum efficiency at high J. A model of a 2D-density of states with exponential tails fits the spectra. The value of T in the active layer was estimated. A new band was detected at high J; it can be caused by non-uniformity of In content in MQWs.