GaAs-AlGaAs Multiple Quantum Wells Research Articles

The properties of hydrogenic donors confined in GaAsAlGaAs multiple quantum wells

Photoluminescence, electronic Raman scattering and far-infrared absorption have been employed in the study of hydrogenic donors in GaAsAlGaAs multiple quantum wells. These measurements indicate that the binding energies of the impurities become larger as the width of the quantum well is reduced. Furthermore, the binding energy depends upon the location of the impurity in the well, with those at the center being the most tightly bound. The magnitude of these effects are in good agreement with theoretical results. These studies suggest that the experimental probes employed should be valuable for the investigation of “spike doping” profiles that have been modified as a result of diffusion or segregation during growth.

The properties of hydrogenic donors confined in GaAs-AlGaAs multiple quantum wells

Abstract Photoluminescence, electronic Raman scattering and far-infrared absorption have been employed in the study of hydrogenic donors in GaAsAlGaAs multiple quantum wells. These measurements indicate that the binding energies of the impurities become larger as the width of the quantum well is reduced. Furthermore, the binding energy depends upon the location of the impurity in the well, with those at the center being the most tightly bound. The magnitude of these effects are in good agreement with theoretical results. These studies suggest that the experimental probes employed should be valuable for the investigation of “spike doping” profiles that have been modified as a result of diffusion or segregation during growth.

Energy loss of two-dimensional electron gas in GaAs-AlGaAs multiple quantum wells by screened electron-polar optic-phonon interaction

Experimental data on the variation of the rate of energy loss of two-dimensional electrons with electron temperature in GaAs-AlGaAs multiple quantum wells have been found to be substantially lower than the values calculated from available theory. We have modified the theory to include overlap function, degeneracy, and screening of electron-polar optic-phonon coupling. The Landau damping of the plasma by single particle excitations and coupling between phonons and plasma are, however, neglected. It is found that inclusion of overlap and screening leads to good agreement between theory and experiment.

3-pJ, 82-MHz optical logic gates in a room-temperature GaAs-AlGaAs multiple-quantum-well étalon

Various pulsed logic functions (nor, xor, etc.) are performed in a high-finesse nonlinear Fabry–Perot étalon containing GaAs-AlGaAs multiple quantum wells at room temperature. Input pulses with energies less than 3 pJ incident on the device produced contrasts greater than 5 : 1 in the nor gate, and relaxation times of about 5 ns allowed us to operate the gates at 82 MHz. Thermal stability was demonstrated in the nor gate even though the device was poorly heat sunk.

Multiple quantum well optical nonlinearities: bistability from increasing absorption and the self electro-optic device

This paper briefly reviews the nonlinear optical and electro-optical properties and applications of GaAs—AlGaAs multiple quantum wells, all of which are compatible with laser diodes or semiconductor electronics or both. They show large nonlinear absorption and refraction (associated with their strong room-temperature exciton resonances) applicable to all-optical devices. They also show large electroabsorptive effects, some of which are unique to the quantum wells at any temperature, which are so strong that optical modulators can be made with micrometre dimensions. A new class of optical bistability (due to increasing absorption) is also reviewed; combination of this with the electroabsorptive effects enables a new mirrorless optical switch called a Self Electro-optic Effect Device (SEED), which sets a new standard for optical switching energies, with energy densities reduced by a factor of six by comparison to even the best resonant cavity devices.

Picosecond relaxation of hot carriers in highly photoexcited bulk GaAs and GaAs-AlGaAs multiple quantum wells

The relaxation rate of hot carriers following picosecond photoexcitation in GaAs-AlGaAs multiple quantum well structures is found to be significantly slower than the corresponding rate for bulk GaAs under high excitations. This is confirmed by a detailed comparison of the hot-luminescence tails for the two cases using picosecond pulse and cw photoexcitations.