Palladium‐based on‐wafer electroluminescence studies of GaN‐based LED structures

Autor: Adam R. Boyd, Carmen Salcianu, Colin J. Humphreys, Ej Thrush, O. Rockenfeller, R. G. Plumb, D. Schmitz, Michael Heuken
Rok vydání: 2008
Předmět:
Zdroj: physica status solidi c. 5:2219-2221
ISSN: 1610-1642
1862-6351
DOI: 10.1002/pssc.200778576
Popis: Electroluminescence (EL) testing of Light Emitting Diode (LED) structures is usually done at the chip level. Assessing the optical and electrical properties of LED structures at the wafer scale prior to their processing would improve the cost effectiveness of producing LED-lamps. A non-destructive method for studying the luminescence properties of the structure at the wafer-scale is photoluminescence (PL). However, the relationship between the on-wafer PL data and the final device EL can be less than straightforward (Y. H Aliyu et al., Meas. Sci. Technol. 8, 437 (1997) [1]) as the two techniques employ different carrier injection mechanisms. This paper provides an overview of some different techniques in which palladium is used as a contact in order to obtain on-wafer electroluminescence information which could be used to screen wafers prior to processing into final devices. Quick mapping of the electrical and optical characteristics was performed using either palladium needle electrodes directly, or using the latter in conjunction with evaporated palladium contacts to inject both electrons and holes into the active region via the p-type capping layer of the structure. For comparison, indium was also used to make contact to the n-layer so that electrons could be directly injected into that layer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Databáze: OpenAIRE
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