A study of zinc doping in metallo-organic chemical vapor deposition of InP

Abstract

Zn-doped InP epitaxial layers, grown by atmospheric pressure metallo-organic chemical vapor deposition using the adduct process, have been characterized by Hall effect, secondary ion mass spectroscopy, and electrochemical profilling techniques. From the results of these measurements the dopant vapor concentration dependence of the room temperature carrier density, net acceptor density, and total Zn atomic density in the layers has been ascertained and the activation energy of the main acceptor level has been measured as 30 meV. A novel technique for measuring the extent of dopant diffusion is described and this has been used to determine diffusion coefficients of Zn of 1–6×10−13 cm2 s−1, values which are much lower than those previously reported. p-n homojunction devices have also been fabricated and these were evaluated by I-V and C-V measurements. The classical diode equation was obeyed over large ranges of current, and ideality factors for the diodes were found to be 1.2–1.5. These results, together with the C-V measurements, show that high quality InP homojunctions can be produced by the adduct technique and the successful use of the material in advanced devices indicates that this is a valuable process for the future.