Gold Schottky contacts on (0 0 2) CdSe films growing on p-type silicon wafer

The thermal evaporation technique has been successfully used for depositing CdSe on p-Si (0 0 1) substrates. X-ray diffraction analysis indicated the hexagonal structure for the growing film along the (0 0 2) plane with c-axis perpendicular to Si-substrates. The average particle size was calculated to be ∼40 nm with a dislocation density at the film surface of 6.25 × 1010 cm−2. The temperature dependent electrical properties of Au Schottky contacts to a-plane CdSe thin films growing on p-Si (0 0 1) were investigated over the temperature range of 160–360 K, which show a rectification behavior. The barrier height (φb), and ideality factor (n), values were found to be 0.863 eV at 360 K to 0.451 eV at 160 K, and 2.48 ± 0.11 at 360 K to 5.18 ± 0.19 at 160 K, respectively. The increasing of φb while decreasing n with the increase of temperature was described by a double Gaussian distribution with two different regions in the temperature range of 240–360 and 160–240 K. Moreover, it was observed that Au/CdSe/Si/Al heterostructure exhibit space charge limited current (SCLC) at all temperatures. The transition voltage (Vx) from ohmic to SCLC is found to be quite dependent on temperature. The defect levels were estimated from the slope of ln J versus 1/T plots, which yield two values of activation energies ΔEd1 = 0.227 ± 0.011 eV in the 240–360 K range and ΔEd2 = 0.128 ± 0.003 eV in the 160–240 K range, respectively.

► Structural and I–V–T characterization of Au/CdSe/p-Si/Al heterostructure.
► Study of Au/CdSe Schottky interface.
► Relation between Schottky barrier heights (φb) and ideality factor (n).
► The observed variation of both φb and n is attributed to spatial barrier inhomogeneities.