Study of band gap narrowing effect in n-GaAs for the application of far-infrared detection

• Published in: Physica. B, Condensed matter Condensed matter, 2002-11, Vol.324 (1), p.379-386
• Main Authors: Luo, H.T, Shen, W.Z, Zhang, Y.H, Yang, H.F
• Format: Article
• Language: English
• Subjects: Band gap narrowing; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Exact sciences and technology; Far-infrared detection; General theory; Iii-v semiconductors; Impurity and defect levels; n-GaAs; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Optical properties of specific thin films; Physics; Theory, models, and numerical simulation; Transmission
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/S0921-4526(02)01428-X

The band gap shrinkage Δ E g of n-GaAs in relation with the doping concentration ( N) is still controversial in various theories and experiments. Most of the experimental results of Δ E g from photoluminescence have already been questioned to have an overestimation by a few tens of meV. We have carried out detailed temperature-dependent transmission experiments on an n-GaAs homojunction far-infrared (FIR) detector structure. By calculating the transmission spectra taking into account the band tail effect, we obtained a 1/3 power rule of Δ E g in n-GaAs by Δ E g=−3.60×10 −8 (eV cm) N 1/3. Our results support Harmon et al.'s experimental Δ E g results from the electrical measurements of np product in n-GaAs (Appl. Phys. Lett. 64 (1994) 502). The yielded Δ E g is employed to calculate the cut-off wavelength λ c and dark current of n-GaAs homojunction FIR detectors to investigate the potential application. We find that n-GaAs is more suitable for a long λ c detector design, and has a similar dark current behavior with that of Si and p-GaAs homojunction FIR detectors.