Heavy- and light-hole band crossing in a variable-strain quantum-well heterostructure

A variable-strain quantum-well semiconductor heterostructure has been designed and studied. Mutually opposite slopes for heavy- and light-hole band edges are obtained by grading the strain within the quantum well from compressive to tensile. A simultaneous red and blue quantum-confined Stark shift for the heavy- and light-hole transitions, respectively, and a unique bias-controlled crossover have been observed by modulation spectroscopy. This indicates that the heavy and light holes experience opposite fields created by the same strain at the same location.