Photovoltaic junction for a solar cell

摘要

A photovoltaic junction for a solar cell is provided. The photovoltaic junction has an intrinsic region comprising a multiple quantum well stack formed from a series of quantum wells separated by barriers, in which the tensile stress in some of the quantum wells is partly or completely balanced by compressive stress in the others of the quantum wells. The overall elastostatic equilibrium of the multiple quantum well stack may be ensured by engineering the structural and optical properties of the quantum wells only, with the barriers having the same lattice constant as the materials used in the oppositely doped semiconductor regions of the junction, or equivalently as the actual lattice size of the junction or intrinsic region, or the bulk or effective lattice size of the substrate. Alternatively, the barriers may contribute to the stress balance.

主权项

1. A monolithic photovoltaic junction for a solar cell, comprising:
first and second oppositely doped semiconductor regions; an intrinsic region disposed between the first and second oppositely doped semiconductor regions, the intrinsic region having an actual lattice size and comprising quantum wells of first and second types and barriers separating each of the quantum wells, the quantum wells of the first type being formed of one or more materials having a lattice constant less than the actual lattice size of the intrinsic region, and the quantum wells of the second type being formed of one or more materials having a lattice constant greater than the actual lattice size of the intrinsic region; and a distributed Bragg reflector, formed of alternate lavers of a semiconductor material of differing refractive indices and disposed adjacent to at least one of the first or the second oppositely doped semiconductor regions, for reflecting light, unabsorbed by the quantum wells, towards the quantum wells.