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From: jws@thumper.mlb.semi.harris.com (James W. Swonger)
Newsgroups: sci.energy,sci.electronics
Subject: Re: solar cells
Message-ID: <1991Jan7.184225.19070@mlb.semi.harris.com>
Date: 7 Jan 91 18:42:25 GMT
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 You don't necessarily have to use Arsenic. There are other N dopants, like
Phosphorus.

 Even if you do use Arsenic, the As in the silicon is going to stay put. The
concentration of As/Si is about 100ppm @ Nd=1E19. The only way to release it
is to eat away the silicon with which it is mixed. In oxygen Si quickly forms a 
passivating oxide layer. HF is not commonly found in nature, so the oxide is 
not going anywhere. Relax. Quit yipping.

 Since solar cells require fewer masking steps they use fewer chemicals and
produce less waste. (Each mask uses a given amount of photoresist, etchant,
stripper, etc).

 A solar cell's life will be a tradeoff between efficiency (minimum metal
coverage of Si) and interconnect life. A well encapsulated cell will escape
corrosion problems. A cell with adequate current density margin on its
metallization will not be subject to catastrophic failure; its lifetime
would be limited by the creep of its junctions.