DIFFUSION OF PHOSPHORUS IN CDTE

The diffusion of phosphorus in CdTe was measured as a function of anne al time and temperature in the temperature range 600-900 degrees C. Th e diffusion anneals were carried out in evacuated silica capsules main ly with traces of radioactive phosphorus in the capsule along with suf ficient cadmium metal to maintain a saturated vapor pressure over the CdTe slice throughout each anneal. The concentration profiles were mea sured using a radiotracer sectioning technique. Diffusion anneals were carried out also using other conditions, including some with excess t ellurium in the capsule in place of the cadmium. The diffusion profile s were single component. The standard erfc function gave satisfactory fits to the profiles which were Fickian in nature except for short ann eal times at intermediate temperatures. When the diffusivity was plott ed on an Arrhenius graph, a straight line was obtained giving an activ ation energy of 2.0 eV. The surface concentration at each temperature was independent of time and varied in value between 1.5 x 10(16) cm(-3 ) at 600 degrees C to 1 x 10(18) cm(-3) at 900 degrees C. When the res ults were plotted on an Arrhenius graph, the results gave a straight l ine with an activation energy of 1.3 eV.