NUMERICAL-ANALYSIS OF CHARGE-TRANSPORT IN SEMIINSULATING GAAS WITH 2 CONTACTS

The de, steady state charge transport in 200-mu m-thick semi-insulatin g GaAs samples with two large whole area metal contacts is calculated numerically. The material:is assumed to have shallow donors and an exc ess of deep accepters. The distributions of the space charge density a nd of electron and hole conductivities are calculated for different el ectron and hole-supplying contacts with different bias voltages. It is found that the contact which injects majority carriers into the semic onductor due to the voltage-bias determines the distribution of the sp ace charge density in a greater volume of the sample than the other co ntact. Consequently, this contact is decisive for the space distributi on of the electric field and the shape of the current-voltage (I-V) ch aracteristic. Comparison is made with experimental observations of the I-V characteristics of one of our detector of particles. (C) 1996 Ame rican Institute of Physics.