InGaN structure influence on efficiency droop
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InGaN structure influence on efficiency droop Oleg Rabinovich National University of Science and Technology “Moscow Institute of Steel and Alloys”, P.O. Box 409, Moscow, 119313, Russian Federation. ABSTRACT Simulation results of InGaN light-emitting diodes and efficiency droop are presented. A special method for investigating the changes in the semiconductor devices characteristics due to different influencing factors is developed. The cause of efficiency droop was detected-large difference in carrier lifetimes. The simulation results are used to suggest several techniques for improving LED efficiency up to 10-15 %. INTRODUCTION Such materials as AIIIBV and AIIBVI attract attention due to their unique properties. AIIIBV and A BVI and their alloys are very interesting and useful as materials for nanoelectronic devices. One of the most significant advantages of these materials are that, for example, the AlInGaN band-gap energy depends on the Indium composition ratio and varies from 1.95 to 6.3 eV at room temperature. For this reason, nitrides have significant potential for applications in short-wavelength electroluminescence and high-temperature, high-power, and high-frequency electronics. The wide band-gap, strong bonds and high thermal conductivity of AIIIBV and AIIBVI make them especially interesting for optoelectronic applications, including full-colour displays, high-density information storage, solar-blind ultraviolet detectors, microwave power, lightemitting diodes (LED) and lasers in the blue and UV spectrum. Despite previous investigations by Hadis Morkos, Shuji Nakamura, Joachim Piprek, Klaus Streubel and Fred E. Schubert, there are still several problems that must be solved. For example LED degradation, efficiency droop and method of obtaining optimum material structure for achieving theoretical maximum luminous flux need to be investigated. II
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In this investigation simulation software SimWindows was used [1]. Distinctive features of this program are as follows: the electrical, optical and thermal properties of devices that are provided via simulation based on exact physical systems; the possibility of simulating different types of double contact devices (LEDs, photodiodes, lasers, etc.) in a 1D approximation based on different materials, such as silicon, germanium, and AIIIBV / AIIBVI solid solutions, etc. Semiconductor devices based on previous materials with structures that could contain many
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layers with quantum-mechanical properties (single or multiple quantum wells) can also be simulated. The structure considered here is a nanoheterostructure (Het.) consisting of layers with quantum-mechanical properties. The simulation program includes two thermal models that calculate either the lattice temperature or electron temperature. The program has an exclusive flexibility for optoelectronic semiconductor device simulations. Drift-diffusion, thermoionic, and tunneling currents are taken into consideration, and the recombination of charge carriers radiating spontaneously and stimulated and non-ra
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