This work studies Te doping effects on the direct bandgap photoluminescence(PL) of indirect Ga_(x)In_(1-x)P alloys(0.72 ≤ x ≤ 0.74). The temperature-dependent PL shows that the energy difference between direct Γ va...This work studies Te doping effects on the direct bandgap photoluminescence(PL) of indirect Ga_(x)In_(1-x)P alloys(0.72 ≤ x ≤ 0.74). The temperature-dependent PL shows that the energy difference between direct Γ valley and indirect X valleys is reduced due to the bandgap narrowing(BGN) effect, and the direct band transition gradually dominates the PL spectra as temperature increases. Carrier thermalization has been observed for Te-doped Ga_(x)In_(1-x)P samples, as integrated PL intensity increases with increasing temperature from 175 to 300 K. The activation energy for carrier thermalization is reduced as doping concentration increases. Both BGN effect and carrier thermalization contribute to the carrier injection into the Γ valley. As a result, the direct band transition is enhanced in the Te-doped indirect Ga_(x)In_(1-x)P alloys. Therefore, the PL intensity of the Ga_(0.74)In_(0.26) P sample with active doping concentration of 9 × 10^(17)cm^(-3)is increased by five times compared with that of a nominally undoped sample. It is also found that the PL intensity is degraded significantly when the doping concentration is increased to 5 × 10^(18)cm^(-3). From cross-section transmission electron microscopy,no large dopant clusters or other extended defects were found contributing to this degradation.展开更多
文摘This work studies Te doping effects on the direct bandgap photoluminescence(PL) of indirect Ga_(x)In_(1-x)P alloys(0.72 ≤ x ≤ 0.74). The temperature-dependent PL shows that the energy difference between direct Γ valley and indirect X valleys is reduced due to the bandgap narrowing(BGN) effect, and the direct band transition gradually dominates the PL spectra as temperature increases. Carrier thermalization has been observed for Te-doped Ga_(x)In_(1-x)P samples, as integrated PL intensity increases with increasing temperature from 175 to 300 K. The activation energy for carrier thermalization is reduced as doping concentration increases. Both BGN effect and carrier thermalization contribute to the carrier injection into the Γ valley. As a result, the direct band transition is enhanced in the Te-doped indirect Ga_(x)In_(1-x)P alloys. Therefore, the PL intensity of the Ga_(0.74)In_(0.26) P sample with active doping concentration of 9 × 10^(17)cm^(-3)is increased by five times compared with that of a nominally undoped sample. It is also found that the PL intensity is degraded significantly when the doping concentration is increased to 5 × 10^(18)cm^(-3). From cross-section transmission electron microscopy,no large dopant clusters or other extended defects were found contributing to this degradation.
