INJECTION AND FIELD-IONIZATION OF TRAPS IN MNGA2SE4 SINGLE-CRYSTALS

This paper discusses the phenomena of injection and field ionization o f traps in MnGa2Se4 single crystals with a resistivity of 10(9)-10(10) Omega . cm, a direct gap of E(gd) = 2.56 eV, and an indirect gap of E (gi) 2.12 eV, obtained by chemical transport reactions. Based on a stu dy of the volt-ampere characteristics of In-MnGa2Se4-In structures in electric fields of up to 10(5) V/cm in the temperature interval 180-36 0 K and the temperature dependence of the electrical conductivity, the following parameters have been determined: the current-carrier concen tration at the cathode is n(k0) = 5.5 X 10(6) - 2 X 10(8) cm(-3) the q uasi-Fermi level is at E(F) = 0.6 eV, the trap concentration is N-1 = 1.2 X 10(14) - 2 X 10(15) cm(-3), the distance from a trap to the maxi mum of the potential barrier is r(m) = 3.7 X 10(-6) cm, and the electr on free path is lambda = 4.7 X 10(-6) cm. It has been established that monopolar injection of current carriers, which are captured by deep t raps, occurs in electric fields less than 10(3) V/cm, whereas ionizati on of these traps takes place in strong electric fields. (C) 1995 Amer ican Institute of Physics.