Vacancy-enhanced intermixing in highly strained InGaAs/GaAs multiple quantum well photodetector

Abstract

Impurity-free vacancy disordering techniques using rapid thermal annealing with electron-beam evaporated SiO2 encapsulant was utilized to study its effect on the optical and electrical properties of the highly strained InGaAs/GaAs quantum well infrared photodetector. The photoluminescence peak is blueshifted and its line width does not increase much, indicating the compositional disordering of the quantum well structure and there is no strain relaxation or minimal deterioration of the heterostructure quality. Both transverse electric and transverse magnetic infrared intersubband transitions are retained and observed after intermixing. The absorption peak wavelength is redshifted from the as grown 10.2 µm to the interdiffused 10.5 and 11.2 µm, for 5 and 10 s annealing at 850 °C, respectively, without appreciable degradation in absorption strength. Theoretical calculations of the absorption spectra are in good agreement with the experimental data. Annealed responsivity spectra of both 0° and 90° polarization are of comparable amplitude but with narrower spectra line width. Dark current of the annealed devices is found to be an order of magnitude larger than the as-grown one at 77 K.