A comparative study of laser and furnace annealing of P + implanted CdTe

Abstract

We have undertaken a comparative study of CW argon ion laser and furnace annealing of P + implanted CdTe. SIMS measurements indicate that laser annealing can produce a noticeable broadening of the impurity profile when increasing the number of annealing pulses. Using a numerical simulation of the diffusion broadening of implanted impurity profiles, we have established that the diffusion coefficient are higher under laser annealing by orders of magnitude compared to furnace annealing ( D LA = 8.94 × 10 -10 cm 2 s -1 at 550°C, D FA = 4.95×10 -15 cm 2 s -1 at 500°C). This result raises the question of photostimulation of impurity diffusion. The electrical activity of the implanted P was estimated from capacitance measurements which give the degree of compensation achieved in n-type In doped material. A maximum acceptor concentration of about (1.6-1.7)×10 17 cm -3 was deduced for both laser and furnace annealed samples. Luminescence spectra of all the samples show the DA band corresponding to the phosphorus acceptor on the Te site. We found that the intensity of the exciton lines exhibited by the laser treated samples is strongest that that observed in the furnace annealed sample. This demonstrates that CW laser annealing is able to remove implantation damage in a better way that furnace annealing.