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Internal quantum efficiency of the samples (a) absolute vs (b) normalized to 1 vs .
[(a)–(c)] Recombination coefficients and (d) , all plotted vs . The dotted line in (b) is the extrapolation of the 460 nm curve at low , based on the shape of the other curves. For all samples peaks at a similar carrier density [dashed line in (d)].
Absorption coefficient under reverse bias , which induces flat bands in the QWs. The 460 and 470 nm samples have the same band edge. All curves show a shape and amplitude similar to that of bulk GaN (dashed line, shown for reference)—in particular, they display a well-defined band edge from which is derived and an excitonic peak. Also note the similarity in inhomogeneous broadening with bulk GaN, which indicates broadening is not dominated by alloy fluctuations in the MQWs.
Experimental (symbols) and calculated (line) values of B at a carrier density vs the polarization field in forward bias condition .
Table of parameters for the MQW samples. [In] is estimated from x-ray diffraction. is measured at low carrier density .
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