Heterostructure for UV LEDs Based on Thick AlGaN Layers
A. V. Sakharov, W. V. Lundin, A. Usikov, U. I. Ushakov, Yu A. Kudriavtsev, A.V. Lunev, Y.M. Sherniakov, N.N. Ledentsov
Ioffe Physical-Technical Institute
This article was received on Monday, June 22, 1998 and
accepted on Friday, September 25, 1998. Abstract
Thick
AlGaN layers and GaN/AlGaN heterostructures were grown by low pressure MOCVD on
(0001) sapphire substrates utilizing a low temperature AlGaN buffer layer. The
distribution of Al in the thick AlGaN layers was observed to be non-uniform as
a function of depth. The Al content gradually increases from the substrate
towards the epilayer surface. Moreover, fluctuations of Al content are also
noticeable. The saturation of impurity-related emission with increasing current
density was observed in EL spectra of LEDs consisting of AlGaN/GaN/AlGaN DH
sandwiched by a 2 µm-thick bottom layer of GaN:Si and 0.5 µm-thick layer
of GaN:Mg. The dominant near-band edge emission of the GaN active layer was
found to be strongly absorbed in the thick bottom layer. Utilizing a 2
µm-thick AlGaN bottom layer instead of the GaN one allowed the absorption
edge to be shifted towards higher energies. A single peak at 362 nm with FWHM
of 14 nm was observed in this type of LED. Luminescence properties of various
types of heterostructures are also discussed.Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 3, 28(1998).
last updated Friday, September 25, 1998 4:13:15 PM.© 1998 The Materials Research Society
