Hans S. Rupprecht

EFFICIENT VISIBLE ELECTROLUMINESCENCE AT 300°K FROM Ga1‐xAlxAs p‐n JUNCTIONS GROWN BY LIQUID‐PHASE EPITAXY

Efficient visible light emitting diodes have been fabricated from Ga1‐xAlxAs. Epitaxial layers were obtained by a modified solution growth technique. External quantum efficiencies of up to 3.3% have been measured at room temperature on diodes, which had their emission at 1.70 eV. The switching time for the light emission at 300°K was measured to be 60 nsec.

Proximate capless annealing of GaAs using a controlled‐excess As vapor pressure source

A new, capless annealing technique for GaAs, which utilizes a controlled‐excess arsenic vapor pressure has been studied. The excess arsenic vapor is provided by the thermal decomposition of InAs and is about 100 times larger than the arsenic pressure of thermally decomposing GaAs for temperatures of 800–900 °C. This excess pressure forces Si implants to activate predominantly on donor sites for doses of (2–50)×1012 cm−2 studied thus far. A SiF+ dose of 5×1012 cm−2 and implant energy of 250 keV annealed at 900 °C for 30 min produced a sheet electron concentration of 3.5×1012 cm−2 and mobility of 4400 cm2 V−1 sec−1. Photoluminescence studies show that the annealed surfaces must be proximate during anneal to avoid buildup of impurities at the surface. A model based on GaAs evaporation and buildup of bulk impurities on the surface is proposed to explain the results.

Junction heating of GaAs injection lasers during continuous operation

The rise of the junction temperature during continuous operation of an injection laser has been measured as a function of current and is discussed for different cases. The dependence of the emitted light power on current is computed from the thermal data and compared with the experiment. The threshold current and the differential quantum efficiency for continuous operation are discussed.

Stimulated emission from Ga 1-x Al x As diodes at 77°K

Ga 1-x Al x As was found to be a suitable material for semiconductor lasers. Stimulated emission from Fabry-Perot type of diodes has been observed at 77°K and 273°K. The highest peak energy of the laser line at 77°K so far is 1.65 eV ( l = 7500 A). The Ga 1-x Al x As material was obtained by a liquid phase epitaxial method, described in a previous paper.