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Comparative study of (0001) and (11-22) InGaN based light emitting diodes

Accepted version
Peer-reviewed

Repository DOI


Type

Article

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Authors

Pristovsek, M 
Humphreys, CJ 
Bauer, S 
Knab, M 
Thonke, K 

Abstract

We have systematically investigated the doping of (11-22) with Si and Mg by metal-organic vapour phase epitaxy for light emitting diodes (LEDs). By Si doping of GaN we reached electron concentrations close to 1020cm-3, but the topography degrades above mid 1019cm-3. By Mg doping we reached hole concentrations close to 5 × 1017cm-3, using Mg partial pressures about 3' higher than those for (0001). Exceeding the maximum Mg partial pressure led to a quick degradation of the sample. Low resistivities as well as high hole concentrations required a growth temperature of 900 °C or higher. At optimised conditions the electrical properties as well as the photoluminescence of (11-22) p-GaN were similar to (0001) p-GaN. The best ohmic p-contacts were achieved by NiAg metallisation. A single quantum well LED emitting at 465nm was realised on (0001) and (11-22). Droop (sub-linear increase of the light output power) occurred at much higher current densities on (11-22). However, the light output of the (0001) LED was higher than that of (11-22) until deep in the droop regime. Our LEDs as well as those in the literature indicate a reduction in efficiency from (0001) over semi-polar to non-polar orientations. We propose that reduced fields open a loss channel for carriers.

Description

Keywords

40 Engineering, 4018 Nanotechnology

Journal Title

Japanese Journal of Applied Physics

Conference Name

Journal ISSN

0021-4922
1347-4065

Volume Title

55

Publisher

IOP Publishing
Sponsorship
Engineering and Physical Sciences Research Council (EP/E035167/1)
Engineering and Physical Sciences Research Council (EP/H019324/1)
Engineering and Physical Sciences Research Council (EP/I012591/1)
Engineering and Physical Sciences Research Council (EP/M010589/1)
Engineering and Physical Sciences Research Council (TS/G001383/1)
This work was supported by EU-FP7 ALIGHT No. NMP-2011-280587. The data to produce the figures can be found under the permanent url https://www.repository.cam.ac.uk/handle/1810/253538.