Enhancement of carrier concentration in As-containing contact layers

A method for forming a contact layer over an opto-electronic device comprising the steps of:

• (a) providing an opto-electronic device;
• (b) locating said opto-electronic device within a process chamber;
• (c) within said process chamber, forming a Zn-doped InGaAs contact layer over said opto-electronic device using a metalorganic vapor phase epitaxy (MOVPE) process, said MOVPE process including AsH3, (CH3)3In, (C2H3)3Ga, and (CH3)2Zn as process gasses, a maximum formation temperature of at least 650° C., and a pressure less than 100 millitorr, said AsH3 being introduced into said process chamber at a flow rate ranging from 50 sccm to 150 sccm;
• (d) after said contact layer is formed, allowing said contact layer to cool to a threshold temperature within the range of 560° C.-580° C. while introducing AsH3 gas into said process chamber at a flow rate not greater than 10 sccm and further introducing at least one of nitrogen and molecular hydrogen into said process chamber;
• (e) once said threshold temperature is achieved, removing said AsH3 from said process chamber while maintaining said flow of said at least one of nitrogen and molecular hydrogen into said process chamber;
• and
• (f) allowing said opto-electronic device to further cool below said threshold temperature.