Measurements of InGaAs metal-semiconductor-metal photodetectors under high-illumination conditions

We report on temporal response measurements of InGaAs metal-semiconductor-metal photodetectors (MSM-PDs) under high-illumination conditions. The peak current efficiency of the MSM-PDs decreases as optical pulse energy increases due to space-charge-screening effects. The screening effect begins to occur at an optical pulse energy as low as 1.0 pJ, as predicted by a recent two-dimensional model. The fall time and full width at half maximum of the impulse response increase as the optical pulse energy increases and decrease as the bias voltage increases. For optical pulse energies between 1.0 and 100 pJ, the rise time displays a U-shaped behavior as the bias voltage increases. This may be associated with the shape of the electron velocity-field characteristic in conjunction with the screening of the dark field by optical generated carriers.