Bias independent heavy- and light-hole degeneracy in InGaAs/InGaAsP quantum wells

We present a type of strained semiconductor quantum-well structure that exhibits bias-independent heavy-and light-hole degeneracy. This effect is achieved by inserting thin layers of highly strained material in an unstrained quantum well. By adjusting the thickness and the position of the highly tensile strained layers, the quantum confined Stark effect for the heavy and light holes can be engineered separately to control the bias dependent polarization properties. Experimental results on such a structure agree well with the theory. These unique bias-dependent polarization properties have important applications in optoelectronic devices when specific polarization properties are required. (C) 1998 American Institute of Physics.