Low temperature Cd diffusion in InP using the leaky tube method

Abstract

Diffusion of cadmium (Cd) acceptors into InP has been carried out, using leaky tube diffusion, achieving specular surfaces and high quality p-n junctions. Acceptor concentration profiles as well as atomic concentration profiles are examined, and the concentration-dependent diffusion coefficient is calculated. Pure Cd is used as the dopant source, and no external source of P is required in the ambient. Cadmium is found to be much less reactive with the InP surface than Zn. High quality p/sup +/-n junctions on the order of 1 to 2 mu m are produced in a controllable manner at 500 degrees C. Secondary ion mass spectrometry shows the atomic and electrically active Cd surface concentrations to differ by a factor of about two at the surface and then become essentially conformal at a concentration of approximately 7*10/sup 17/ cm/sup -3/.<>