Investigation of composition fluctuations in GaN:Mg using optical transmission spectroscopy, near-field scanning optical microscopy, and scanning Kelvin probe microscopy
Investigation of composition fluctuations in GaN:Mg using optical transmission spectroscopy, near-field scanning optical microscopy, and scanning Kelvin probe microscopy
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DOI：
10.1063/1.1948527
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发表时间：
2005-07
影响因子：
3.2
通讯作者：
B. Han;B. Wessels;M. Ulmer
中科院分区：
文献类型：
--
作者：
B. Han;B. Wessels;M. Ulmer
Composition fluctuations in GaN:Mg have been investigated by optical transmission spectroscopy, near-field scanning optical microscopy (NSOM), and scanning Kelvin probe microscopy (SKPM). An Urbach tail is observed in the optical transmission spectrum of heavily Mg-doped GaN, with the magnitude of Urbach energy increasing with increasing compositional/potential fluctuations. From the relationship between the Urbach energy and the potential fluctuation magnitude, the spatial size of the compositional fluctuations in GaN:Mg (with the average Mg concentration of ∼4×1019cm−3) is calculated to be 220nm. The nanoscale compositional fluctuations are determined by NSOM and SKPM. A spatial variation of the transmission mode NSOM intensity is observed with a characteristic wavelength of ∼300nm, which is attributed to the inhomogeneous distribution of Mg. The normalized root-mean-square (rms) fluctuation of the transmission mode NSOM intensity for heavily Mg-doped GaN is a factor of 5 greater than that for undoped G...
