Abstract-THz-excitation spectroscopy technique for band-offset determination

V. Karpus, R. Norkus, R. Butkutė, S. Stanionytė, B. Čechavičius, A. Krotkus

Fig. 3 Experimental setup for THz excitation spectroscopy measurements.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-26-33807

The experimental THz-excitation spectroscopy technique for determining heterojunction band offsets is suggested. When photoexcited electrons gain sufficient energy to pass the potential barrier corresponding to a conduction band offset, an amplitude of THz-emission pulse sharply increases, which allows for direct measurements of the offset value. The technique is applied for determining GaAsBi-GaAs band offsets. The deduced conduction band offset of GaAsBi-GaAs heterojunction has about 45% of an energy gap difference at the Bi concentrations x <0.12 investigated.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Terahertz pulse generation from (111)-cut InSb and InAs crystals when illuminated by 1.55-μm femtosecond laser pulses

I. Nevinskas, K. Vizbaras, A. Trinkūnas, R. Butkutė, and A. Krotkus

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-42-13-2615

Terahertz (THz) pulse generation from p-InAs, p-InSb, and n-InSb epitaxial layers are investigated using 1.55-μm wavelength femtosecond laser pulses for photoexcitation. The samples are of (111) crystallographic orientation resulting in anisotropic photoconductivity. Experiments have shown that THz generation in InAs is mainly due to anisotropic photocurrent in the surface electric field while a dominant mechanism in InSb is optical rectification. At high optical excitation fluencies, InSb is more efficient than p-InAs. In the presence of an external magnetic field, (111) InSb has exhibited promising viability as an alternative to the photoconductive antenna emitter in a THz time-domain-spectroscopy (THz-TDS) system.

© 2017 Optical Society of America