Microstructure of highly p-type doped GaN sub-contact layers for low-resistivity contacts

R. Kroger, J. Dennemarck, T. Bottcher, S. Figge, D. Hommel

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

The effect of a highly Mg doped subcontact layer on top of GaN grown by metal organic vapor phase epitaxy and its interface to a Pd/Au contact layer was investigated by means of transmission electron microscopy and electrical characterization techniques. Use was made of prior investigations of the Mg doping characteristics, which showed the existence of a segregation related defect free layer even for doping levels as high as 5x10(-19) cm(-3), which thickness depends on the Mg to Ga molar precursor flow ratio. For a given subcontact layer thickness of 15 nm a critical precursor molar flow ratio of 0.035 resulted in a smooth surface showing an interfacial layer indicating a Pd/Ga alloying. This layer resulted in a contact resistivity as low as 2x10(-5) Omega cm(2). For a flow ratio of 0.070 the surface was found to be rough due to defect formation resulting in a contact resistivity as high as 10(-3) Omega cm(2) similar to the value obtained without subcontact layer. Moreover, the metallization layer showed in all cases a texture of the 111 lattice planes with respect to the 0002 planes of the GaN.
Original languageUndefined/Unknown
Title of host publicationGaN, AIN, InN and Their Alloys
EditorsC. Gil B. Kuzuhara M. Manfra M. Wetzel
PublisherCambridge University Press
Pages411-415
Number of pages5
Volume831
Publication statusPublished - 2005

Publication series

NameMaterials Research Society Symposium Proceedings

Bibliographical note

Times Cited: 0 Symposium on GaN, AIN, InN and Their Alloys held at the 2004 MRS Fall Meeting NOV 29-DEC 03, 2004 Boston, MA Mat Res Soc

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