TITLE

The Franz–Keldysh effect in shocked GaN:Mg

AUTHOR(S)
Peng, H. Y.; McCluskey, M. D.; Gupta, Y. M.; Kneissl, M.; Johnson, N. M.
PUB. DATE
March 2003
SOURCE
Applied Physics Letters;3/31/2003, Vol. 82 Issue 13, p2085
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The band gap of uniaxially strained semi-insulating GaN:Mg has been examined using time-resolved optical transmission measurements in shock-wave experiments. For longitudinal stresses between 2.9 and 4.6 GPa, the absorption edge broadened significantly. Such a broadening is consistent with the presence of large piezoelectric fields (Franz-Keldysh effect) generated due to shock compression. For stresses greater than 4.6 GPa, however, the absorption edge remained relatively sharp. The sharp absorption onset suggests the presence of free charge carriers that screen the piezoelectric field, thereby suppressing the Franz-Keldysh effect. These observations indicate that electrical breakdown occurs at a field of 1 MV/cm. One possible mechanism that could result in free carriers is the dissociation of Mg-H complexes under the very high piezoelectric fields.
ACCESSION #
9377428

 

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