Investigation of laser-beam-induced photocurrent in planar two-dimensional n-p-n structures

The magnitude of photocurrent induced in two-dimensional n-p-n structures has been measured depending on the position of the focused laser beam incident at their surface. Studied samples were fabricated of p-doped GaAs/In_0.11Ga_0.89As/Al_0.33Ga_0.67As heterostructure by the local overcompensation doping with silicon. These structures exhibit high photosensitivity and the value of photocurrent induced in them varies linearly with the change in the position of the incident beam in almost the entire space between the two p-n junctions. An absolute position sensor based on 2D n-p-n structures has been designed and the spatial resolution of this coordinate-sensitive element was estimated.