Microwave energized deposition process with substrate temperature control for the fabrication of P-I-N photovoltaic devices

A method for the manufacture of an p-i-n type photovoltaic device of the type comprising a body of substantially intrinsic Group IV semiconductor alloy interposed between two oppositely doped semiconductor layers, said method including the steps of:

• I. Depositing a body of semiconductor material of a first conductivity type upon a substrate;
• II. Depositing a body of a substantially intrinsic Group IV semiconductor alloy upon said body of semiconductor :material of a first conductivity type, by a microwave energized glow discharge deposition process comprising:
• a. providing a deposition system having a plasma region defined therein, said system including a conduit for introducing a process gas there into and a source of of microwave energy for activating said process gas in said plasma region so as to decompose said gas and form a plasma therefrom;
• b. supporting said substrate, with said body of semiconductor material of a first conductivity type thereupon, in said plasma region;
• c. maintaining said substrate at a temperature in excess of 400.degree. C.;
• d. introducing a process gas having a Group IV semiconductor element therein into said system;
• e. maintaining the process gas at a process pressure which is less than atmospheric;
• f. inputting microwave energy into said system at a power level at least sufficient to sustain a plasma of said process gas at said process pressure in said plasma region, whereby said microwave energy creates a plasma from, and decomposes, the process gas so as to deposit a layer of said Group IV semiconductor alloy material on the body of semiconductor material of a first conductivity type;
• and
• III. Depositing a body of semiconductor material of a second conductivity type, opposite said first conductivity type, upon said layer of Group IV semiconductor alloy material.