Acknowledgements; Contents; 1 Introduction; 2 Background; 3 Experimental Procedure; 4 Photoluminescence of Disordered Semiconductors; 5 Hopping Relaxation of Excitons in Disordered Semiconductors: Energy Scaling of Disorder; 6 Quantitative Description of the Photoluminescence Thermal Quenching in Ga(AsBi); 7 Summary; Bibliography; List of Publications