Diffusion Limited AC Quantum Efficiency of Photodiodes.
Abstract
It is shown that the minority carrier diffusion contribution to the ac quantum efficiency of a semiconductor photodiode is a function of the product of the absorption coefficient (alpha) and the diffusion length (L) of the semiconductor material. Since L is essentially constant (e.g. over a considerable temperature range) for a given detector, the dependence of the ac quantum efficiency on alpha L becomes significant near the absorption edge of the semiconductor material where the value of alpha decreases rapidly with increasing wavelength and can change, due to a shift of the band edge, with temperature. The diffusion portion of the ac quantum efficiency is investigated for a variety of input signals: impulse, step, square, and triangular pulses, and sinusoidally modulated signals. In general, the magnitude and cut-off frequency degrade as alpha decreases. The results are applied to photodiodes of silicon, germanium, and mercury cadmium telluride.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1975
- Accession Number
- ADA013549
Entities
People
- C. E. Burke
Organizations
- United States Army Communications-Electronics Command