Band-edge electroluminescence from amorphous/crystalline silicon heterostructure solar cells

Heterojunction solar cells with thin emitter layers of a-Si:H(n+) on monocrystalline p-type silicon exhibit electroluminescence with power efficiencies of up to 0.3%. Above 50 K the emission is intrinsic with no differences between various samples and the integrated intensity increases with temperature different from the expectation for an ideal diode. At T < 40 K the behavior of various samples differs appreciably. Numerical simulations demonstrate a strong influence of the density of interface states, which determines the emission intensity and its temperature dependence. The results show that good performance as LED is related to a high value of the open circuit voltage.