High speed laser crystallization of particles of photovoltaic solar cells

Abstract

A system and method for enhancing the conversion efficiency of thin film photovoltaics. The thin film structure includes a photovoltaic absorbent layer covered by a confinement layer. A laser beam passes through the confinement layer and hits the photovoltaic absorbent layer. The laser can be pulsed to create localized rapid heating and cooling of the photovoltaic absorbent layer. The confinement layer confines the laser induced plasma plume creating a localized high-pressure condition for the photovoltaic absorbent layer. The laser beam can be scanned across specific regions of the thin film structure. The laser beam can be pulsed as a series of short pulses. The photovoltaic absorbent layer can be made of various materials including copper indium diselenide, gallium arsenide, and cadmium telluride. The photovoltaic absorbent layer can be sandwiched between a substrate and the confinement layer, and a molybdenum layer can be between the substrate and the photovoltaic absorbent layer.

What is claimed is: 
     
         1 . A system for fabricating thin film photovoltaics, the system comprising:
 a thin film structure comprising a photovoltaic absorbent layer covered by a confinement layer;   a laser generating a laser beam that travels along an optical path to hit the photovoltaic absorbent layer by passing through the confinement layer, the confinement layer being substantially transparent to the laser beam;   wherein the confinement layer confines a laser induced plasma plume and creates a localized high-pressure condition for the photovoltaic absorbent layer.   
     
     
         2 . The system of  claim 1 , wherein the laser beam is pulsed to create localized rapid heating and cooling of the photovoltaic absorbent layer. 
     
     
         3 . The system of  claim 1 , wherein the photovoltaic absorbent layer comprises at least one of a copper indium diselenide layer, a gallium arsenide layer, and a cadmium telluride layer. 
     
     
         4 . The system of  claim 1 , wherein the thin film structure further comprises a substrate, the photovoltaic absorbent layer being sandwiched between the substrate and the confinement layer. 
     
     
         5 . The system of  claim 4 , wherein the thin film structure further comprises a molybdenum layer between the substrate and the photovoltaic absorbent layer. 
     
     
         6 . The system of  claim 1 , wherein the confinement layer is made of glass. 
     
     
         7 . The system of  claim 1 , wherein the laser beam is scanned across a specific region of the thin film structure. 
     
     
         8 . The system of  claim 7 , further comprising an X-Y stage for scanning the target relative to the laser beam. 
     
     
         9 . The system of  claim 7 , further comprising a movable mirror for scanning the laser beam across the thin film structure. 
     
     
         10 . The system of  claim 1 , wherein the laser is a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser.