Effect of carrier confinement and doping in quantum well tunnel junctions

Quantum well tunnel junctions have attractive properties for the design of multi-junction solar cells and represent a good alternative to homo-junction tunnel diodes. Tunnel junctions based on InAlAs quantum wells were grown strain balanced on InP with varying well and barrier thicknesses. We characterized their current voltage characteristics and found that devices with thicker well and thinner tunnel barrier performed best provided the doping profile across the structure is accurately controlled. We explain the effects of barrier and well thicknesses due to quantum confinement as well as doping using a Poisson-Schrodinger model coupled to a non-local tunneling model that were implemented in a numerical drift-diffusion solver.