STUDIES ON EXCIMER-LASER DOPING OF GAAS USING SULFUR ADSORBATE AS DOPANT SOURCE

Excimer laser doping of GaAs using sulphur adsorbate as a dopant sourc e is demonstrated. Box-like n-type layers of depths of about 100 nm wi th carrier concentration as high as (2 similar to 3) x 10(19) cm(-3) a re formed. Passivation of GaAs using a (NH4)(2)S-x solution for 40 min followed by sublimation of the excess sulphur atoms in high vacuum re sult in an effective dopant for controllable n-type doping. The sample s are irradiated using a KrF excimer laser in a N-2 gaseous environmen t. Secondary ion mass spectrometry (SIMS) measurements show that sulph ur is successfully incorporated in the GaAs. The sheet resistance is c ontrolled by adjusting,the laser energy fluence and number of laser pu lses. Rutherford backscattering spectrometry with channeling (RBS/C) a lignment measurement indicates that lattice damage is undetectable for N-2 gas pressures of 760 Torr.