A study of p-type dopants for InP grown by adduct MOVPE

• Published in: Journal of crystal growth 1984-09, Vol.68 (1), p.102-110
• Main Authors: Nelson, A.W., WestBrook, L.D.
• Format: Article
• Language: English
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/0022-0248(84)90404-4

Zn, Cd and Mg have been studied as suitable dopants for the preparation of p-type InP by adduct MOVPE. Electrical characterisation and SIMS measurements have been used to show that the log p versus log(dopant precursor vapour flow) plots are characterised by slopes of 1 2 , 1 and 2 for Zn, Cd and Mg respectively. These results were explained well by a recently proposed trapping theory, together with our measurements of dopant diffusion coefficients ( D Zn =(1–6)·10 -13 cm 2 s -1, D Cd =(0.4 −1.4)× 10 -15 cm 2 s -1, D Mg = (2–6)×10 -15 cm 2 s -1). Cd doping was also studied as a function of growth temperature and was found to be dominated by surface desorption, leading to higher doping levels at lower growth temperatures. I−V measurements on p−n + homojunctions revealed ideality factors of 1.2−1.5 for Zn and Cd junctions and 1.5−2.5 for Mg doped junctions. It was concluded, from a critical appraisement of the doping characteristics, that Cd (obtained from the pyrolysis of DMCd) exhibited the nearest to ideal behaviour of the dopants studied.