Pulsed response of Ga0.47In0.53As photodiode structures with a submicron gap between interdigital electrodes

The effects of miniaturisation of optoelectronic devices makes simple size-scaling methods ineffective. A two-dimensional model demonstrates that the main problem in metal–semiconductor–metal (MSM) diode structures with small interelectrode gaps is the small depth of penetration of an electric field into the active region of a diode. This results in different rates of electron and hole collection at the contacts and delays the pulsed response of a photodetector. Self-consistent two-dimensional analysis is made of the photocarrier motion in the active region of an MSM diode structure and of the characteristics of the pulsed response of Ga_0.47In_0.53As MSM photodiodes. Ways of improving this response are discussed. The calculated results are compared with experiments.