Quantum-confined strain gradient effect in semiconductor nanomembranes

Semiconductor nanomembranes can exhibit strain gradients that lead to quantum confinement effects similar to the well known quantum-confined Stark effect (QCSE) in semiconductor quantum wells. The deformation of square well into triangular well potential leads to modifications of the exciton resonance, but important differences between the quantum-confined strain gradient effect (QCsgE) and the QCSE include (i) the versatility of the QCsgE in which conduction and valence bands can have different slopes (even reverse slopes are possible), and (ii) the fact that in the QCsgE exciton shifts are determined by the gradients in the heavy-hole and light-hole energies as well as a gradient in the heavy-hole and light-hole coupling.