Polarization engineering of c‐plane InGaN quantum wells by pulsed‐flow growth of AlInGaN barriers

Polarization-field reduction in c-plane InGaN multi-quantum well (MQW) structures is achieved by pulsed-flow growth of quaternary AlInGaN barriers using metalorganic vapor phase epitaxy (MOVPE). The pulsed-flow growth allows for precise control of the quaternary composition at very low growth rate. In photoluminescence (PL) experiments a blue-shift of the MQW emission wavelength is observed by successive adjustment of the AlInGaN barriers toward reduced polarization mismatch to the InGaN quantum wells. Accordingly, we find a decreasing radiative lifetime by time resolved cathodoluminescence (TRCL). The application of AlInGaN as barrier material instead of conventional GaN is limited by plastic relaxation. While for InGaN-QWs emitting in the violet-blue spectral region, fully polarization-matched AlInGaN barriers can be realized, for long-wavelength (green spectral region) severe lattice relaxation is observed leading to inferior optical properties as compared to binary GaN barriers. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim