William Angerer - Department of Physics and Astronomy - University ...

105
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Figure -1.11: Device to measure temperature of GaN during low temperature photoluminescence.
The thick wires represent the four leads (two current, two voltage) to
the carbon-glass resistor.
pIe. In the region near the band gap, ,...., 400 nm, the doped samples exhibit a similar
behavior as the undoped sample. Again this is attributed to donor-acceptor reCOffibination.
C'nIike the spectra from the undoped sample, the doped sample spectra
display a wide feature at ",2.2 eV. In contrast to the DA recombination feature. this
feature is insensitive to temperature. This yellow band luminescence is ubiquitous in
GaN samples. The oscillations in the yellow band are due to a micro cavity formed
by the front and back surfaces of the GaN film [61].
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