Space-Charge–Limited Currents in Evaporated GaS Thin Films

Space-charge–limited–current (SCLC) measurements have been
performed at room temperature on n-GaS thin films. Ohmic conduction was
predominant at low applied fields, with the free electron concentration
no ≈ 3.25×10 14 m –3. Two deep electron traps have been found at 0.51 and 0.56
eV below the conduction band with concentrations ranging between 10 21 and
10 22 m-3. Two distinct activation energies ΔE1 and ΔE2 have been detected in
the temperature range between 250 K and 400 K. The former represents a
shallow level with ΔE1 = 0.32 eV. The latter one, ΔE2 = 0.63 eV, shows a
deeper level located in the band gap. A comparison was made between the
results of this work and data quoted by various authors with different
techniques. The expected chemical defects are considered in data analysis.