Pulse anneal method for solar cell

DETAILED DESCRIPTION What is claimed: 1.
The method of making a solar cell which comprises the steps of depositing on a substrate a first layer of n-type amorphous silicon, followed by a second layer of amorphous silicon containing carbon atoms, followed by a third layer p-type amorphous silicon, and annealing the entire structure by rapidly heating with radiant thermal energy for a short period of time, said carbon atoms minimizing crystallization of said second layer and maintaining high light absorption.
2.
The method of claim 1 in which the first layer is formed by plasma decomposition of SiH.
sub.
4 with 0.
3% PH.
sub.
3, the second layer by plasma decomposition of SiH.
sub.
4 with 10% CH.
sub.
4 and the third layer by plasma decomposition of SiH.
sub.
4 and 0.
3% B.
sub.
2 H.
sub.
6.
3.
A solar cell formed by the method of claim 2.




Description:
This invention relates generally to solar cells made of semiconductor material and more particularly to an annealing process for such solar cells.
In the production of semiconductor solar cells it is often advantageous or essential to include an annealing step.
This annealing step typically involves the insertion of the semiconductor material into a furnace, maintained at an elevated temperature, for a period of time.
It is believed that this serves to activate impurities and dopants in the semiconductor to modify their electronic properties; to cause the dopants to diffuse or migrate in the material in a controlled manner; to produce grain growth or coalescence of the semiconductor material; or to heal defects in the semiconductor lattice.
However, certain undesirable effects may accompany the intended consequences of the annealing.
As the dopants are activated, they may redistribute such that they subsequently degrade the solar cell performance.
Impurities or contaminants may diffuse into the active region of the solar cell and impair its performance.
In addition to producing deleterious effects, long annealing times may render impossible the fabrication of certain classes of solar cell structures, such as annealed multilayer thin film devices