P-Type Semiconductor Zinc Oxide Films Process for Preparation Thereof, and Pulsed Laser Deposition Method Using Transparent Substrates

Abstract

A p-type semiconductor zinc oxide (ZnO) film and a process for preparing the film are disclosed. The film is co-doped with phosphorous (P) and lithium (Li). A pulsed laser deposition scheme is described for use in growing the film. Further described is a process of pulsed laser deposition using transparent substrates which includes a pulsed laser source, a substrate that is transparent at the wavelength of the pulsed laser, and a multi-target system. The optical path of the pulsed laser is arranged in such a way that the pulsed laser is incident from the back of the substrate, passes through the substrate, and then focuses on the target. By translating the substrate towards the target, this geometric arrangement enables deposition of small features utilizing the root of the ablation plume, which can exist in a one-dimensional transition stage along the target surface normal, before the angular width of the plume is broadened by three-dimensional adiabatic expansion. This can provide small deposition feature sizes, which can be similar in size to the laser focal spot, and provides a novel method for direct deposition of patterned materials.

1 . An apparatus for depositing transparent thin films and direct deposition of patterned structures on a substrate, comprising;
 a pulse laser source,   a beam delivery system for guiding said laser through the substrate and focusing it on a target,   a transparent substrate onto which material ablated or evaporated from said target is deposited, and   a translation system for moving said substrate relative to said target.   
   
   
       2 . An apparatus as claimed in  claim 1 , further comprising a substrate heating system, comprising a CW infrared heating laser. 
   
   
       3 . An apparatus as claimed in  claim 1 , wherein said target is mounted to a target holder, and said target holder is a multi-target apparatus capable of moving multiple targets successively to a target location. 
   
   
       4 . An apparatus as claimed in  claim 1 , wherein said translation system positions said substrate at a variable distance from said target, said variable distance ranging from 10 μm to 30 cm.