Impurity-free intermixing of InGaAs/GaAs-strained multiple quantum well infrared photodetectors

Abstract

Interdiffusion effect has been investigated in highly strained InGaAs/GaAs multiple quantum well (MQW) IR photodetector. Impurity-free interdiffusion techniques was utilized via rapid thermal annealing (RTA) using electron- beam evaporated SiO2 cap layers at temperature 850 degrees C to study the optical and electrical properties of the interdiffused photodetector. Photoluminescence (PL) spectrum is blue shifted and PL linewidth remains almost the same, indicating no strain relaxation and deterioration of the heterostructure quality. Both transverse magnetic and transverse electric IR intersubband transitions are retained and observed after intermixing. The absorption peak wavelength is red shifted continuously from the as grown 10.20 to the interdiffused 10.5 and 11.17 micrometers , respectively, without appreciable degradation in absorption strength for 5 and 10 s annealing. Annealed responsivity spectra of both 0 degrees and 90 degrees polarization are of compatible amplitude and red shifted but with narrower spectra linewidth. Dark current of the annealed devices is found to be an order of magnitude large than the as-grown one at 77K.