POLARIZATION ANISOTROPY IN ELECTROABSORPTION AND ELECTROLUMINESCENSE OF ORDERED GAINP AND THEIR DEVICE APPLICATIONS

摘要

We have studied the polarization dependence of the absorption, electroabsorption (Franz-Keldysh effect) and electroluminescence of double hetero p-i-n structures based on ordered GaInP. An ordering induced shift of the Franz-Keldysh spectra of up to 12meV has been observed between the electroabsorption spectra for light polarized parallel to the [011] and [01-1] crystal direction, respectively. These measurements allow to get useful information about the valence band structure, like valence band splitting and band gap reduction. Moreover, the polarization dependence can also be utilized for polarization sensitive optoelectronic devices. Based on the strong polarization anisotropy of the absorption coefficient, a polarization threshold switch with an high photoconductive gain can be realized. This device shows a switching contrast of almost 50 dB and a maximum sensitivity of about 3 dB/degree. Light emitting diodes with ordered GalnP in the active region show a polarized light output. Depending on the ordering parameter a contrast ratio of up to 2.0 dB has been observed between the [011] and [01-1] polarized part of the emitted light.