Temperature-dependent terahertz radiation from the surfaces of narrow-gap semiconductors illuminated by femtosecond laser pulses

✍ Scribed by G. Molis; R. Adomavičius; A. Krotkus

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 143 KB
• Volume: 403
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2008.07.005

✦ Synopsis

Temperature-dependent increase of the terahertz (THz) electric field emitted from the surfaces of optically pumped narrow-gap semiconductors InAs, InSb, and Cd x Hg 1Àx Te is presented. In the case of Cd 0.2 Hg 0.8 Te increase up to 15-17 times has been observed, when cooling the sample from the room temperature to close to liquid-helium temperatures, and THz emission from this material becomes comparable to that of p-InAs emitter. This effect was explained in terms of the increased photoexcited electron excess energy due to the positive temperature coefficient for energy bandgap of Cd x Hg 1Àx Te, as well as by weaker surface field screening and carrier-carrier scattering. Temperature-dependent modification of the shape of THz pulses emitted from InSb surfaces has been observed and attributed to plasma oscillation of the cold electrons.