Simulation and design of light emitting structures based on III-V nitrides
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Date
2006-04
Authors
Norzaini Zainal
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Abstract
The objective of this work is to obtain high performance III-V nitride based blue
light emitting diode (LED) designs through simulation study. The simulations of LED
designs are implemented by using SILVACO simulation program. The LED designs
are simulated from basic p-n homojunction structure, to double heterostructure and
eventually the use of multiquantum well in the LED design. The simulated LED
structures are conducted by ATLAS device simulator in SILVACO. The parameters of
LED structure are varied and optimized to obtain high performance LED. This
optimization study involves aspects such as different energy barrier composition,
thickness of active region, doping in active region, doping in confinement regions,
thickness of top confinement region, thickness of quantum wells and quantum barriers,
number of quantum wells and several approaches to improve and achieve high
emission output of LED. Our simulation results revealed several parameters that had
been optimized. For homojunction LED structure, the optimum thickness of p-GaN
layer was 0.1 pm, for double'heterojunction LED, the optimum thickness of In013Ga087N
active region was 10 nm without the use of AIGaN cladding layers. Meanwhile, the
optimum doping in the active region and the confinement region were 5x1018 cm,3 and
optimum thickness of p-GaN cladding layer was 0.3 ~lm.
Based on the results, high performance LED had been obtained by using
multiquantum wells incorporated with the optimized parameters. Initially, the LED
performance decreased as number of InGaN quantum well increased. Some
approaches to improve the LED emission output for higher number of the InGaN
quantum wells were adopted. In the end of this simulation work, few types of
preferable LED designs were suggested; one can have single spot high performance
quantum well LED such as SOWs LED structure which are doped n-type in the
selected quantum barriers. However, if multiple emission spots are desirable, one can
have SOWs LED with undoped quantum barriers sharing high efficient emission in first
and second well but wasted in the third, fourth and fifth wells. Another design
suggested the preferable LED have p-doped region in the third quantum barrier in the
3QWs LED for a more homogeneous emission.
Description
Keywords
To obtain high performance III-V nitride , based blue light emitting diode (LED)