Texturing semiconductor substrates
Semiconductors are textured with aqueous solutions containing non-volatile alkoxylated glycols, their ethers and ether acetate derivatives having molecular weights of 170 or greater and flash points of 75° C. or greater. The textured semiconductors can be used in the manufacture of photovoltaic devices.
1. A method comprising:
a) providing a semiconductor substrate; and
b) applying an aqueous solution comprising one or more compounds chosen from alkoxylated glycols, their mono-methyl ether and mono-methyl ether acetate derivatives comprising a molecular weight of 170 g/mole or greater and a flash point of 75° C. or greater, and one or more alkaline compounds to the semiconductor substrate to texture the semiconductor substrate.
2. The method of claim 1 , wherein the one or more compounds chosen from alkoxylated glycols, their mono-methyl ether and mono-methyl ether acetate derivatives have a formula:
RO(C x H 2x O) m Y (I)
wherein R is —CH 3 or —H, Y is —H or —C(O)CH 3 , and m is an integer of 3 or greater and x is an integer of 3 to 6.
3. The method of claim 1 , wherein the alkoxylated glycols have a formula:
HO(CH 2 CH 2 O) n H (II)
wherein n is an integer of 3 or greater.
4. The method of claim 1 , wherein the one or more alkaline compounds are chosen from hydroxides and alkanolamines.
5. The method of claim 1 , further comprising one or more alkali metal chlorides or one or more silicates, or mixtures thereof.
6. A method comprising:
a) providing a semiconductor substrate;
b) texturing a surface of the semiconductor substrate with an aqueous solution comprising one or more compounds chosen from alkoxylated glycols, their mono-methyl ethers and mono-methyl ether acetate derivatives comprising a molecular weight of 170 g/mole or greater and a flash point of 75° C. or greater, and one or more bases;
c) doping the semiconductor substrate to provide a p/n junction;
d) depositing an anti-reflective layer on the textured surface;
e) selectively etching the anti-reflective layer to expose portions of the textured surface to form a pattern; and
f) depositing one or more metal layers on the exposed portions of the textured surface.
7. The method of claim 6 , wherein the one or more metal layers is gold, silver, copper or nickel.
8. The method of claim 6 , wherein the silicon containing substrate is a photovoltaic device, electrodes, ohmic contact, interconnection line, Schottky barrier diode contact, an optoelectronic component, components for optical and electrochemical detectors/sensors, catalysts, ohmic contacts, and interconnection lines.
9. An aqueous texturing solution consisting essentially of one or more compounds chosen from alkoxylated glycols, their mono-methyl ether and mono-methyl ether acetate derivatives having a weight average molecular weight of 170 g/mole or greater and a flash point of 75° C. or greater, one or more alkaline compounds and water.