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We investigated the suitability of aluminum nitride (AlN) for surface passivation and protection of gallium arsenide (GaAs), using a low-temperature passivation method. By varying the plasma power (100, 200 W) during etching, we found that 200 W produced better passivation. Using X-ray photoelectron spectroscopy, we quantitatively demonstrate that etching the GaAs at 200 W almost removed the GaAs oxide layer. To further study the surface passivation of GaAs, we deposited an AlN film by plasma-enhanced atomic layer deposition using trimethylaluminum and ammonia precursors at 250 °C. AlN passivation did not effectively smooth the GaAs surface, but did increase its photoluminescence intensity. This study shows that AlN coating by plasma-enhanced atomic layer deposition is a promising low-temperature method for GaAs surface passivation. [ABSTRACT FROM AUTHOR]

In this work, we perform a sulfur chemical passivation on GaAs substrate, which leads to a change in the photoluminescence (PL) owing to a reduction of surface states. By varying the reaction time of passivation, we can modify the chemical bonds of the GaAs surface and reduce the surface depletion region thickness, which strongly affects the emission efficiency of the GaAs band edge. Based on systematic PL measurements and energy band model with surface states, the sulfur passivation also enhances the number of free and bound excitons. Therefore, sulfur passivation is important to improve the performance of GaAs-based optoelectronics devices. [ABSTRACT FROM AUTHOR]