Photocarrier spreading at a p-n junction

Continuous wave and pulsed optical beam induced current measurements were carried out on n-InP/n-InGaAs/n-InP double heterostructures which contain large areas of diffused InGaAs p-n junctions. The flat cw photocurrent and illumination-position independence of the transient photocurrent response, observed when the optical source spot illuminates a floating diode, demonstrates the effect of photocarrier spreading in a p-n junction. The very long photocarrier spreading length observed at low optical power may be an important parasitic coupling mechanism which should be considered in the isolation-design of integrated optoelectronic devices.