Alfred Adams conducts pioneering work on the application of high-pressure techniques to the study of semiconducting materials. Alfred has done much to advance the use of strain as an important variable in understanding the basic physics of devices. His contributions include the first demonstration of the T–L–X ordering of the conduction band minima in gallium arsenide, the first direct observations of scattering by the central cell potential of impurities, the proposal and experimental confirmation of intervalence band absorption as an important loss mechanism in semiconductor lasers and the prediction that the threshold current in a quantum-well laser can be greatly reduced if the wells are grown in a state of compressive stress. These latter ideas are currently being pursued vigorously around the world where they are resulting in lasers having greatly enhanced performance.