EFFECTS OF ANNEALING ON DAMAGE IN ALGAAS INDUCED BY ELECTRON-CYCLOTRON-RESONANCE SF6 CHF3 PLASMA-ETCHING/

The change in sheet resistance of an SF6/CHF3 plasma-exposed AlxGa1-xA s (x = 0.30, 0.15) epilayer before and after annealing was investigate d and compared with that for GaAs. The sheet resistance of plasma-expo sed AlxGa1-xAs (x = 0.30, 0.15) increases further after 300 degrees C annealing, while that of GaAs remained unchanged. After 450 degrees C annealing, the resistivity of plasma-exposed AlxGa1-xAs(x = 0.30) was still higher, while damage in AlxGa1-xAs (x = 0.15) and GaAs had compl etely vanished. The increased resistivity in AlxGa1-xAs (x = 0.30, 0.1 5) after annealing was mainly due to further carrier reduction after a nnealing was mainly due to further carrier reduction by magnification of the damaged region. The effect of annealing on He plasma-exposed Al GaAs was similar to that for SF6/CHF3-plasma-exposed AlGaAs, which sug gests that the increased sheet resistance after annealing is related t o incorporated low-mass ions, such as He and H. The 4.2 K photolumines cence measurements revealed a new spectral peak near 1.70 eV after ann ealing, and the peak intensity for the SF6/CHF3 and He plasma-exposed samples was prominent. These results suggest that in-diffusion of poin t defects by light ions during the annealing extends the carrier reduc tion in AlGaAs to greater depth.