Jose Gonzalez Mejia

US Patent:

57669643, Jun 16, 1998

Filed:

Dec 22, 1995

Appl. No.:

8/579074

Inventors:

Ajeet Rohatgi - Marietta GA
Parag Doshi - Altanta GA
John Keith Tate - Lawrenceville GA
Jose Mejia - Atlanta GA
Zhizhang Chen - Duluth GA

Assignee:

Georgia Tech Research Corporation - Atlanta GA

International Classification:

H01L 3118

US Classification:

437 2

Abstract:

Processes which utilize rapid thermal processing (RTP) are provided for inexpensively producing high efficiency silicon solar cells. The RTP processes preserve minority carrier bulk lifetime. tau. and permit selective adjustment of the depth of the diffused regions, including emitter and back surface field (bsf), within the silicon substrate. In a first RTP process, an RTP step is utilized to simultaneously diffuse phosphorus and aluminum into the front and back surfaces, respectively, of a silicon substrate. Moreover, an in situ controlled cooling procedure preserves the carrier bulk lifetime. tau. and permits selective adjustment of the depth of the diffused regions. In a second RTP process, both simultaneous diffusion of the phosphorus and aluminum as well as annealing of the front and back contacts are accomplished during the RTP step. In a third RTP process, the RTP step accomplishes simultaneous diffusion of the phosphorus and aluminum, annealing of the contacts, and annealing of a double-layer antireflection/passivation coating SiN/SiO. sub. x. In a fourth RTP process, the process of applying front and back contacts is broken up into two separate respective steps, which enhances the efficiency of the cells, at a slight time expense.