“Aluminum free nitride laser diodes grown by plasma assisted MBE”

Abstract

Progress of laser displays depend on availability of reliable and efficient laser diodes (LDs) operating in true-blue and green spectral range. The active region of long wavelength nitride based LDs contains high indium content InGaN quantum wells (QWs), therefore extensive efforts are made to understand the growth mechanism of InGaN. Due to the very demanding growth conditions — high growth temperature, high N precursor overpressure — until recently, the leading technology for LDs growth was Metal Organic Vapour Phase Epitaxy (MOVPE). On the other hand, the understanding of the low temperature growth mechanisms for nitrides in Plasma Assisted Molecular Beam Epitaxy (PAMBE) has renewed interest in this technology [1]. Application of the high Nitrogen flux during the PAMBE growth of InGaN leads to the flat growth front of high In content InGaN layers and increases the quantum efficiency of QWs [2,3]. For green LDs, the strong decrease of the differential gain is observed and fabrication of such diodes was only possible due to the substantial reduction of the internal light losses. Therefore the new LDs design which can increase the confinement of the optical modes and further decreases internal losses can be beneficial for next generation of nitride based LDs.