MULTI-NARY GROUP IB AND VIA BASED SEMICONDUCTOR
Methods and devices are provided for forming an absorber layer. In one embodiment, a method is provided comprising of depositing a precursor material onto a substrate, wherein the precursor material may include or may be used with an additive to minimize concentration of group IIIA material such as Ga in the back portion of the final semiconductor layer. The additive may be a non-copper Group IB additive in elemental or alloy form. Some embodiments may use both selenium and sulfur
1 . A method for forming a thin film absorber layer, the method comprising:
providing a base having a front surface and a back surface;
depositing a precursor layer over the front surface of the base, wherein the precursor layer comprises Ag, Cu, and at least one Group IIIA material;
selenizing the precursor layer to form a silver-based selenide;
incorporating S into the silver-based selenide to form a sulfur containing senary material for the thin film absorber layer;
wherein the incorporating step comprises providing an evaporation source to generate an S vapor, wherein an amount of S is determined by temperature of the evaporation source; wherein source temperature is at least about 230 C.
2 . The method of claim 1 wherein:
wherein silver-based material in the silver-based selenide film regulates incorporation of sulfur species into the senary material.
3 . The method of claim 1 further comprising:
annealing the precursor layer to densify the layer and form a nascent absorber layer of reduced thickness prior to the step of fully selenizing.
4 . The method of claim 3 wherein:
the nascent absorber layer of reduced thickness has a non-uniform distribution of elements, with a first region type and a second region type.