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Understanding The Role Of Defects In Limiting The Minority Carrier Lifetime In Sic

Published online by Cambridge University Press:  10 February 2011

W. A. Doolittle ,
A. Rohatgi ,
R. Ahrenkiel ,
D. Levi ,
G. Augustine  and
R. H. Hopkins
W. A. Doolittle
Affiliation:
Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, GA 30332–0250
A. Rohatgi
Affiliation:
Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, GA 30332–0250
R. Ahrenkiel
Affiliation:
National Renewable Energy Laboratory, Boulder CO
D. Levi
Affiliation:
National Renewable Energy Laboratory, Boulder CO
G. Augustine
Affiliation:
Northrop Grumman, Pittsburgh PA. alan.doolittle@ece.gatech.edu
R. H. Hopkins
Affiliation:
Northrop Grumman, Pittsburgh PA. alan.doolittle@ece.gatech.edu
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Abstract

Deep level Transient Spectroscopy (DLTS), Electron Beam Induced Current (EBIC), EBIC Diffusion Length Mapping (EBIC-DLM) and contactless Photoconductive Decay (PCD) were used to characterize both bulk substrates and epitaxially grown Silicon Carbide films. Traps as deep as 0.93 eV were observed via DLTS. These traps may play a role in the persistent photoconductivity effect. EBIC reveals the electrical activity of the well known triangular defects. However, only some of these defects display electrical activity consistent with that of 3C-SiC inclusions, others do not. Additionally, not all defects identified in the EBIC images are observable in the topographic SEM image, possibly indicating a new, yet unidentified defect. EBIC revealed the electrical activity of defects including micro-pipes, dislocations (or possibly growth step edge decoration), surface polish damage, and bulk defects. Diffusion length maps of SiC indicate wide variations in diffusion length on both microscopic and macroscopic scales. EBIC-DLMindicatedepitaxial 4H SiC resulted in diffusion lengths from 0.1 to 3 μm, while bulk values were less than 0.07 μm. PCD measurements indicate tens of nanosecond to microsecond variations in lifetime. Lifetime verses injection level variations are observed and explained on the basis of trap energy. The injection level dependence of lifetime was observed at various nitrogen doping concentrations. Finally, electron beam annealing is found to dramatically improve the minority carrier lifetime in epitaxial SiC.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 483: Symposium E – Power Semiconductor Materials & Devices , 1997 , 197
Copyright
Copyright © Materials Research Society 1998

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References

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