Well-resolved sharply structured luminescence spectra at 1.54 μm were observed in erbium-implanted GaP, GaAs, InP, and Si. The optical transitions occur between the weakly crystal field split spin-orbit levels, 4I13/2→4I15/2, of Er3+(4f11). Typical spectral linewidths in GaAs are 2 cm−1(0.25 meV) at 6 K and 11 cm−1(1.36 meV) at room temperature.
The feasibility of producing erbium-doped silicon light-emitting diodes by molecular beam epitaxy is demonstrated. The p-n junctions are formed by growing an erbium-doped p-type epitaxial silicon layer on an n-type silicon substrate. When the diodes are biased in the forward direction at 77 K they show an intense sharply structured electroluminescence spectrum at 1.54 μm. This luminescence is assigned to the internal 4f–4f transition 4I13/2→4I15/2 of Er3+ (4f11).
Thermoelectric (TE) properties of InxGa1−xN alloys grown by metal organic chemical vapor deposition have been investigated. It was found that as indium concentration increases, the thermal conductivity decreases and power factor increases, which leads to an increase in the TE figure of merit (ZT). The value of ZT was found to be 0.08 at 300K and reached 0.23 at 450K for In0.36Ga0.64N alloy, which is comparable to those of SiGe based alloys. The results indicate that InGaN alloys could be potentially important TE materials for many applications, especially for prolonged TE device operation at high temperatures, such as for recovery of waste heat from automobile, aircrafts, and power plants due to their superior physical properties, including the ability of operating at high temperature/high power conditions, high mechanical strength and stability, and radiation hardness.
We report on the experimental investigation of the potential of InGaN alloys as thermoelectric (TE) materials. We have grown undoped and Si-doped In 0.3 Ga 0.7 N alloys by metalorganic chemical vapor deposition and measured the Seebeck coefficient and electrical conductivity of the grown films with the aim of maximizing the power factor (P). It was found that P decreases as electron concentration (n) increases. The maximum value for P was found to be 7.3 9 10 À4 W/m K 2 at 750 K in an undoped sample with corresponding values of Seebeck coefficient and electrical conductivity of 280 lV/K and 93 (X cm) À1 , respectively. Further enhancement in P is expected by improving the InGaN material quality and conductivity control by reducing background electron concentration.
The characteristic 1.54-μm emission from the rare-earth element erbium implanted in GaAs, InP, and GaP was investigated through 10-K photoluminescence essentially as a function of anneal temperature, time, and method. The strip-heater, forming-gas, and quartz-ampoule anneal methods were utilized in the range of 400 to 1000 °C. Erbium-related emissions were observed from 1.48 to 1.64 μm and were observable at emission temperatures of up to 260 K for InP:Er and 296 K for GaP:Er and GaAs:Er. Out of the three semiconductors, GaAs:Er was observed to exhibit the highest optical activation using a square-profile implantation technique. Dependent on the anneal method, optimum Er emissions occurred between 650 and 800 °C for GaAs, for InP between 575 and 625 °C, and for GaP between 800 and 950 °C. In general, the forming-gas anneal method proved most successful; however, maximum luminescence including sharper emission lines was achieved through the strip-heater method. This method, with an anneal time of 10 s, showed also the importance of short-time anneals in GaAs:Er, results which were also paralleled by isothermal anneals of InP:Er. The difference in emissions at different anneal temperatures and times gives preliminary evidence of different Er3+ centers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.