Polarization Effects in the (Electro)absorption of Ordered GaInP and their Device Applications
Electro-absorption measurements provide a powerful tool to obtain information on the electronic structure of ordered GaInP. Due to their high resolution of approximately 1 meV, they allow the exact determination of transition energies at the Γ point. We are able to give accurate values for ordering-relevant parameters like the band gap reduction, valence band splitting and the position of the split-off valence band. Moreover, the exact energetic position of zone edge folded states could be determined. We deduce that only about 80% of the band gap reduction is due to the ordering-induced lowering of the conduction band. The polarization anisotropy of ordered GaInP is used to demonstrate novel device concepts such as detectors and (bistable) switching devices, which are sensitive to the polarization direction of the optical input signal. The electrical output signal of the switches is independent of the light intensity. It changes by many orders of magnitude as a function of the polarization angle of the incident light. A switching contrast of 50 dB and a maximum sensitivity of about 10 dB/degree have been demonstrated.
Key wordsPolarization anisotropy polarization detectors and -switches
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