Noncontact Characterization of Carrier Mobility in Long-Wave Infrared HgCdTe Films With Terahertz Time-Domain Spectroscopy

• Published in: IEEE transactions on terahertz science and technology 2024-07, Vol.14 (4), p.466-475
• Main Authors: Refvik, Nils B., Jensen, Charles E., Purschke, David N., Pan, Wenwu, Simpson, Howe R. J., Lei, Wen, Gu, Renjie, Antoszewski, Jarek, Umana-Membreno, Gilberto A., Faraone, Lorenzo, Hegmann, Frank A.
• Format: Article
• Language: English
• Subjects: Carrier density; Carrier mobility; Charge carrier processes; Conduction bands; Conductivity measurement; Dielectric measurement; Effectiveness; II-VI semiconductor materials; Mercury (metals); Optical properties; Spectroscopy; Substrates; Temperature dependence; Temperature measurement; Terahertz communications; terahertz time-domain spectroscopy (THz-TDS); Time domain analysis
• ISSN: 2156-342X; 2156-3446
• DOI: 10.1109/TTHZ.2024.3393627

We use terahertz time-domain spectroscopy to measure the complex dielectric function of long-wave infrared Hg 1- x Cd x Te films ( x = 0.18, 0.20, 0.22) as a function of temperature in a noncontact manner. Using a Drude-Lorentz model fit to the measured complex transmission function combined with a Kane model description of the band structure, we obtain the temperature-dependent conduction band carrier density, effective mass, scattering time, and carrier mobility for all three Hg 1− x Cd x Te films. The optical properties of a bare substrate of Cd 0.96 Zn 0.04 Te were also measured in the terahertz region. The high quality of the Hg 1− x Cd x Te films is demonstrated by ultrahigh mobilities exceeding 10 5 cm 2 V −1 s −1 and ionized donor densities less than 3 × 10 15 cm −3 at temperatures below 100 K.