The Avalanche-Mode Superjunction LED

Abstract

Avalanche-mode light-emitting diodes (AMLEDs) in silicon (Si) are potential light sources to enable monolithic optical links in standard CMOS technology, due to the large overlap of their electroluminescent (EL) spectra with the responsivity of Si photodiodes. These EL spectra depend on the reverse electric field. We present AMLEDs employing the superjunction (SJ) assisted reduced surface-field (RESURF) effect, which increases the uniformity of their electric field profile. Consequently, the EL area of these lateral devices is significantly enlarged as compared with conventional AMLEDs. Electrical and opticalmeasurements demonstrate RESURF, as predicted by TCAD simulations, and show a direct link between EL-intensity (optical power per unit device area) and the field profile. Contrary to a conventional AMLED, the breakdown voltage of the avalanche-mode SJ-LED scales with the device length. Furthermore, the brightest SJ-LED, with a lateral intensity of ~30 mW cm−2 at an electrical power ( ${P}_{\textrm {AMLED}}$ ) of 0.1W, shows a twofold higher internal quantum efficiency and a threefold higher EL-intensity compared with the conventional AMLED for the same ${P}_{\textrm {AMLED}}$ . This particular SJ-LED also shows an optimum radiative recombination efficiency at a current density of around ~800 A cm−2.