Fabrication a device Hetrojunction of Compound Cu2ZnSnS4 Films and study the Electrical Properties of it by Pulse Laser Deposition
The prepared samples of compound thin-film by pulse laser deposition method were achieved. . Powders of (CZTS) copper (Cu), zinc (Zn), tin (Sn) and Sulfur (S) of and then compressing by approximately 3 tons in Pellets form. The samples were ablated by using Neodymium-YAG laser with different laser energies (400mJ, 500mJ, 600mJ, 700mJ, 800mJ) and number of pulses (300)pulse, frequency (6Hz)and wavelength(1064) nm obtained the plasma plume at 10-5mbar pressure. Results indicate by continuous conductivity and using Hall phenomena systems and I-V characteristics in light and dark states .The electrical results show that continuous conductivity indicated that conductivity increases with increasing temperature, and decreases conductivity with increasing film thickness when increasing laser energy, It was found that the electrical conductivity has two values for the activation energy Ea1 and Ea2 this is due to two types of transfers ,The first activation energy is the transition between positional levels within the energy gap that occurs by the jump method and the second activation energy represents the transition between farther levels within the energy gap by the method of thermal stimulation. carrier type changes of the films of the CZTS compound from p- type to n-type when the laser energy increases, so the density of carriers, conductivity and resistivity is disparate, while the mobility decreases with increasing laser energy. The I-V characteristics in light and dark states Show that there is decrease with the disparit of current values in the dark state and an increase in the sensitivity of the samples after lighting in the forward and reverse bias ,and the best efficiency efficiency of heterojunction is with a value of (4.1402813) when depositing the type (n) film of the CZTS sample on the Si (p) substrate at laser energy (800mJ). As for the efficiency of the heterojunction prepared, it is noted that it increases at the energy of the laser (800mJ) Si (p) /CZTS800mJ (n) then it starts to decrease when the (n) film is deposited on the (n) substrate, Because the electron density increases when the laser energy increases. The optical energy gap of Cu2ZnSnS4 compound thin films was a direct allowed transition and decrease of values (2.8-1.8eV), if the laser energy is increased, also the increasing of thickness from (130.26 - 176.83 ±7) nm of the film as a result to the increase laser energy.