Photonic transitions (1.4 eV–2.8 eV) in silicon p(+) np(+) injection-avalanche CMOS LEDs as function of depletion layer profiling and defect engineering

Abstract

p+ np+ CMOS Si LED structures were modeled in order to investigate the effect of various depletion layer profiles and defect engineering on the photonic transitions in the 1.4–2.8 eV, 450–750 nm regime. Modeling shows that by utilizing a short linear increasing E-field in the p+ n reverse-biased junction with a gradient of approximately 5 X 105 V cm-1. µm-1, and injecting carriers from an adjacent p+ n junction, increased localized optical yield by a factor 50–100. A number of device designs were realized using CMOS 0.35 m technology. The device design involves normal CMOS design and processing procedures with no excessive microdimensioning. The current devices operated in the 6–8 V, 1 µA–2 mA regime, and yield emission intensities of up to 100 nW µm-2. The current emission levels are about three orders higher than the low-frequency detectability limit of Si CMOS p-n detectors of corresponding area, which make diverse electrooptical applications such as MOEMS devices, and diverse optical signal processing and wave-guiding and the development of “smart chips” feasible in standard CMOS integrated circuitry.