Different from the case for polar (0001) Inx Ga1-x N multiple quantum wells (MQWs), the effective radiative lifetimes (τR,eff) at 8 K of violet (V: 3.15 eV), purple (P: 3.00 eV), and blue (B: 2.83 eV) emission peaks in nonpolar (1 1- 00) Inx Ga1-x NGaN MQWs fabricated on various GaN templates were found to be nearly independent of InN molar fraction x being approximately 1 ns. The result indicates the absence of polarization fields parallel to the MQW normal. For each luminescence peak, the effective nonradiative lifetime (τNR,eff) at room temperature of the MQWs grown on "Ga-polar" wings of the GaN template prepared by lateral epitaxial overgrowth (LEO) was longer than that for the MQWs grown on "N-polar" wings, windows, or on conventional GaN templates, which had high density basal plane stacking faults and threading dislocations. Since τR,eff was little affected by the presence of defects, the increase in τNR,eff brought fivefold improvement in the equivalent internal quantum efficiency ( int eq) of V peak. Because B peak was mostly generated from defective areas, the increase in int eq was not so remarkable (29%-36%). However, these values are approximately twice that reported for (11 2- 0) InGaNGaN MQWs grown on LEO GaN templates [Onuma, Appl. Phys. Lett. 86, 151918 (2005)].
|ジャーナル||Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures|
|出版ステータス||Published - 2007|
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