TABLE OF CONTENTS I. Harrison
February 1999
The diffusion profiles for Cr, Cu, Au and Fe in InP are very similar and resemble those found for Cr and Fe into GaAs [1, 2]. The profiles can be broken down into two parts [1]. In the high concentration part, which extends from the surface, the concentration of the dopant falls very rapidly with distance, whilst in the low concentration part which extends much further into the crystal, there is little variation with depth. The drop from the high surface concentration to the bulk concentration occurs approximately within the first 40 ?m for all the dopants. The actual distance depends on dopant, diffusion temperature and time. Since the profiles in this region could not be described by a complementary error function, no diffusion coefficients have been determined for any of the dopants. It is generally accepted that when a dopant has a very high diffusion coefficient it most likely diffuses via the interstitial mechanism and so the diffusion process for these atoms into InP involves the interstitial species.
The surface concentration of Cr obtained after an 850 C 60 minute diffusion was approximately 3 10 20 cm -3 and the concentration in the bulk was approximately 5 10 15 cm -3. C-V measurements, however, indicate that the Cr is not electrically active [3]. This lack of electrical activity contrasts with the growth...
