Evaluation of H-plasma and thermal oxide desorption procedures for MBE regrowth of an InP/InGaAs/InP quantum well

An InGaAs single quantum well structure has been used to investigate the effect of H-plasma exposure for oxide removal and subsequent regrowth on InP surfaces. In addition, the H-plasma desorption is compared with the usual technique of thermal desorption of the oxide. Assessment of the optical quality of the regrowth interface has been achieved by photoluminescence (PL), photoluminescence excitation (PLE) and photoreflectance (PR) spectroscopy studies of the quantum well grown directly on the regrowth interface. It is shown that the effect of the H-plasma itself on the InP surface can be minimized by applying a positive bias of +30 V to the substrate or by annealing the substrate. For both the H-plasma and the thermal surface cleaning treatments, the regrowth procedure on air/UV - ozone exposed samples introduces non-radiative defects which strongly degrade the room-temperature PL efficiency. The regrowth procedure also induces a defect-related peak in the low-temperature PL spectra, 15 meV below the quantum well intrinsic PL line. The defect concentration is higher in the case of the H-plasma desorption than in thermal desorption, as deduced from PL measurements. The PLE and PR measurements confirm that the interface disorder is also higher in the H-plasma cleaned sample.