Al0.3Ga0.7As/GaAs quantum well samples, irradiated by (100 eV) hydrogen ions at low exposure, have shown improved luminescence for times greater than two years, when stored at room temperature in atmosphere. In situ temperature programmed desorption (TPD) was used to investigate the desorption of AsH3 from an oxidized AlGaAs surface treated by hydrogen ions. Surface modification determined by TPD and Auger electron spectroscopy measurements was correlated with ex situ photoluminescence measurements to further determine the reasons underlying the long-term room temperature durability of this treatment,as well as the stability of the hydrogen ion passivation at elevated temperatures. Results indicate the importance of the native oxide of the substrate, present during the hydrogenation process, and which may serve as an over-passivation layer. However, the thermal stability study also indicates that this over-passivation layer is not thick enough to prevent the degradation of the underlying substrate at elevated temperatures.