p–n junctions in the surface region of silicon obtained by evaporation of silicon in ultrahigh vacuum

Abstract

The electrical and photoelectrical properties of the surface region of n-type of silicon after evaporation in vacuum for obtaining an atomically clean surface are studied. It is shown that the effective values of hole mobility in p-layers are independent of layer thickness down to 0.2 μm at the effective concentration of acceptors of 1017 to 1018 cm−3 and 294 K if the p-region thickness is changed at the expense of time of silicon evaporation. A profile of electrical active acceptor and donor impurities from the surface deep into the silicon bulk is determined by the method of layer-by-layer etching and of C–U characteristics. According to this profile there is a built-in electrical field in a greater part of the space adjacent to the metallurgical boundary of this p–n junction (in comparison with a diffusion one). This favours drift separation of minor radiation-generated current carriers, that is important in creating high-sensitive and fast-responding photoreceivers. Laboratory samples of photoreceivers with the given detective ability at the wavelength of 1.06 μm equal to 2 × 1012 cm Hz1/2/W (294 K, 64 Hz, 1.22 Hz) are obtained.