Epitaxial growth and electrical characterization of germanium

Ge homojunctions were deposited by means of Metal Organic Vapour Phase Epitaxy (MOVPE) on Ge substrates at 550 degrees C and 675 degrees C, using AsH(3) as n-type dopant. Ge(n)/Ge(p), GaAs(n)/InGaP(n)/Ge(n)/Ge(p) and Ge(n)/Ge(p)/Ge(p) structures were prepared and studied, where n and p identify the layer or substrate doping. Vertical mesa junctions were obtained on the above structures by using conventional photolithographic and evaporation techniques. The junctions were characterized by I-V measurements under dark and illumination conditions and by EBIC technique. It has been observed that the samples grown at lower temperature showed better rectifying I-V characteristics and light conversion efficiency while EBIC results may suggest that a high As diffusion is present in the samples grown at higher temperature.