Study of Photocurrent in the Two-Dimensional n–p–n Structure by Scanning Laser Microscope S. G. Petrosyan a and A. M. Khanbekyan b* a Russian–Armenian University, Yerevan, Armenia b Institute for Physical Research, NAS of Armenia, Ashtarak, Armenia * akhanbekyan@gmail.com Received April 11, 2017 Abstract⎯The photocurrent induced by the local excitation of the light beam focused up to 0.17 μm on the surface of a semiconductor element in the planar structure with two p–n junctions, that is, with the use of the so-called scanning laser microscopy technique, has been studied experimentally. The linear dependence of the photocurrent on the coordinate of the beam center is obtained. The high sensitivity of the structure enables to detect the displacement of the order of tens nanometers. DOI: 10.3103/S106833721703015X Keywords: semiconductor, p–n junction, photocurrent, laser microscopy 1. INTRODUCTION The sensors for movements, counting, size, etc., play an important role in the automation of production. In so doing, the methods of reading information and miniaturizing the dimensions of the sensors are of particular importance, which would allow installing sensors in any geometrically small and limited space. Non-contact sensors, including the so-called position-sensitive sensors, are especially promising, because they allow to obtain information without affecting the very operation of the device or installation. When two-dimensional semiconductor structures with the bipolar conductivity, in which the p- and n- regions are in the same plane, are illuminated with the focused optical (laser) radiation from the spectrum of its intrinsic absorption, it is possible the appearance of the transverse photocurrent. On the basis of such structures with the two-dimensional electron and hole gas, the position-sensitive elements with a linear dependence of the photovoltage on the displacement of the beam along one or two coordinate axes have been studied [1–3]. There are other types of position-sensitive sensors. In [4], the conditions for recording the photocurrent that linearly depends on the displacement of the exciting beam were investigated theoretically and experimentally. The investigation of the photocurrent dependence of semiconductor sensor on the base of InGaAs with the laser excitation in the infrared region was carried out in [5], where an essential dependence of the photocurrent on the size and shape of the focused spot of exciting laser radiation was established. In [6], the origination of a transverse photocurrent was theoretically studied, when the laser beam locally excited the surface of the n–p–n structure. It is shown that the sign of the photocurrent depends on the coordinate of the center of the exciting light spot. The conditions, when the photocurrent magnitude is linearly-dependent function on the coordinate of the center of the exciting light beam, have been found. ISSN 1068–3372, Journal of Contemporary Physics (Armenian Academy of Sciences), 2017, Vol. 52, No. 3, pp. 281–285. © Allerton Press, Inc., 2017. Original Russian Text © S.G. Petrosyan, A.M. Khanbekyan, 2017, published in Izvestiya Natsional'noi Akademii Nauk Armenii, Fizika, 2017, Vol. 52, No. 3, pp. 383–389. 281