Theoretical Studies on TM-Polarized Light Emission for Ultraviolet BAlGaN/AlN Optoelectronic Devices

The transverse-magnetic (TM) light emission characteristics of ultraviolet B
_x
Al
_y
Ga
_1-x-y
N/AlN quantum well (QW) structures with several different Al contents (x = 0.7-0.9) were theoretically investigated using the multiband effective-mass theory. The TM-polarized spontaneous emission peak of BAlGaN/AlN QW structures is found to be significantly enhanced with the inclusion of the boron. In particular, in the case of the QW structure with a relatively low Al content (y = 0.7), the light intensity is about three times larger than for the conventional QW structure. This can be explained by the decrease in the internal field, in addition to the change of the characteristics of the topmost valence subband.