Accession Number : ADP007885

Title :   Strong Photo-Optic Effects in Periodically Delta-Doped InGaAs/GaAs Multiple Quantum Well Structures,

Corporate Author : CALIFORNIA INST OF TECH PASADENA

Personal Author(s) : Larsson, A. ; Maserjian, J.

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : Semiconductor materials exhibiting strong photo-optic effects are attractive for devices intended for parallel all-optical computing and signal processing. The use of quantum well (QW) structures in combination with periodic doping has provided large changes in the optical absorption and refractive index with weak excitation intensities. The periodic doping spatially separates photogenerated electrons and holes leading to long recombination lifetimes and consequently large free carrier concentrations. Depending on the structure design, these free carriers can be used for exciton quenching and band filling or Stark shifts of the excitonic resonance in the QWs. For array devices, operating with the light incident normal to the surface of the wafer, strong effects per unit length of the epitaxial material are desired to limit the total thickness of the structure to reasonable values. Periodically doped structures with short periods are therefore needed. However, as the thickness of the doped layers approaches the mean distance between the dopants, fluctuations in the modulation depth of the conduction and valence band potentials occur which reduces the carrier lifetimes. Here we show that strong photo-optic effects can be achieved in short period structures through the use of periodic delta-doping. By localizing the dopants in planes the statistical spread of the doping atoms is reduced leading to a deeper and more uniform modulation of the conduction and valence band potentials. This reduces the probability for tunneling as well as for thermally assisted recombination.

Descriptors :   *EXCITONS, *ELECTROOPTICS, ABSORPTION, ARRAYS, ATOMS, DEPTH, DOPING, ELECTRONS, FILLING, INTENSITY, LAYERS, LENGTH, LIGHT, MATERIALS, MEAN, MODULATION, OPTICS, PROBABILITY, PROCESSING, QUENCHING, REFRACTIVE INDEX, RESONANCE, SEMICONDUCTORS, SIGNAL PROCESSING, SIGNALS, STRUCTURES, SURFACES, THICKNESS, UNIFORMS, VALENCE BANDS, WAFERS, CHARGE CARRIERS, TUNNELING(ELECTRONICS).

Subject Categories : Electrooptical and Optoelectronic Devices
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE