Laser Assisted Photodeposition of Gold on Semiconducting Material

ABSTRACTRecently, much interest has been created in laser driven chemical reactions and their application towards photodeposition of thin films of metals on semiconducting substrates. The next logical step is to verify the capability of this technique in making adequate electrical contacts for microelectronic fabrications and for circuit writing. Some work in this direction has been reported for Iron and Tungsten. However, deposition of gold has not been reported so far, even though it is very significant from the technological point of view. Therefore, we are proposing here a method for photodeposition of gold.this pupose, Pyridine gold (III) trichloride was found to be adequated and it was prepared by a conventional method, then dried under vacuum for 48 hours. A concentrated solution was made by dissolving it in Dimethyl sulfoxide. A tiny drop of it was put on the substrate and exposed to radiation 488 nm, obtained from an argon ion laser. The time of photodeposition depends upon the power of the beam; for 2 watt/mm2 and for four to six minutes of continuous exposure, good, low noise, reliable and nearly ohmic contacts were obtained.The method is found to be suitable for both conventional and non conventional semiconductors such as ZnTe, doped and undoped ZnSe, and diluted magnetic semiconductors such as Zn1−xMnxSe for which normally used methods are not applicable. The present technique can also be extended to the hiqh Tc superconductor YBa2Cu3O7. The possible mechanism of photodeposition is also discussed.