HYPERTHERMAL (30-500 EV) C-BEAM DOPING INTO GAAS DURING MOLECULAR-BEAM EPITAXY( ION)

Ion-beam doping of GaAs with hyperthermal (30-500 eV) carbon ion (C+) has been investigated using a combined ion beam and molecular beam epi taxy (CIBMBE) system. The CIBMBE system is a combination technique bet ween a low-energy ion accelerator and a solid-source MBE, which are co nnected under ultra-high vacuum (UHV) condition. C+-doping was carried out during GaAs MBE growth at substrate temperature of 550 degrees C with the same C+ beam current density. Grown layers were characterized by low-temperature (2 K) photoluminescence and room temperature Hall effect measurements, and it was revealed that the incorporation behavi or of C significantly depends on the acceleration energy of C+ (E(C+)) . The highest net hole concentration (\N-A - N-D\) was obtained at E(C +)=170 eV. In the energy range of E(C+) < 170 eV, \N-A - N-D\ slightly increased as E(C+) increased, and for E(C+) > 170 eV \N-A - N-D\ dram atically decreased with increasing E(C+) which can be explained in ter ms of enhanced sputtering effect. On the other hand, ion-beam induced radiation damages were observed for E(C+) > 170 eV.