Searching for optimum conditions in the laser writing of small ohmic contacts

Microscopic ohmic contacts are made by laser chem. vapor deposition of platinum on a Pyrex substrate. The elec. cond. of the deposited metal stripes is measured as a function of the laser power, the writing speed, and the organometallic vapor pressure. The latter appears to be the key parameter for producing contacts with low resistance at high writing speeds. Even on these transparent substrates there is no apparent advantage in using light at 350 nm, where photolysis may in principle play a significant role, over using visible light where photolysis is not effective.