Implantation of Li+ and Na+ into PbTeSe for current confinement in PbTeSe/PbSnTe ridge waveguide lasers

Ion implantation of both Li+ and Na+ into n-type PbTe0.92Se0.08 has been used to convert this material to p-type. Li+-implanted samples achieved carrier-type conversion without annealing, while Na+ implanted samples required an anneal at 350 °C before carrier conversion was attained. Hall measurements at 77 K on Li+-implanted, n-type PbTe0.92Se0.08, annealed at 250 °C, indicated an estimated activation efficiency of 11%, and achievement of a hole concentration of 5×1018/cm3. The implantation of Li+ into the top layer of a PbTe0.92Se0.08(n)/PbTe0.82Se0.18Te(p) /PbTe0.92Se0.08(p) double heterostructure laser diode test structure resulted in a factor of 20 increase in series resistance at 200 mV, when compared to the series resistance of a similar unimplanted structure at the same bias voltage. The implanted structure did not exhibit breakdown until voltages exceeding 800 mV had been applied. These results suggest that ion implantation of Li+ into the top cladding layer of PbTeSe/PbSnTe laser diodes can be used to significantly reduce current spreading.