Terahertz Radiation Mechanism of Native n-Type InN with Different Carrier Concentrations

Abstract

The polarity and mechanism of terahertz radiation from native n-type InN excited by femtosecond optical pulses are investigated. The optical properties, electron concentrations, and crystalline quality are characterized by photoluminescence and Raman scattering spectra. The electron concentrations are estimated to be between 0:35 Â 10 19 and 3:87 Â 10 19 cm À3 . The polarity of terahertz radiation field from the samples with higher electron concentrations is opposite to that from p-InAs, indicating that the dominant radiation mechanism is the drift current. However, the samples with lower electron concentrations show the same polarity as p-InAs. Under this condition, the radiation mechanism is dominated by the photo-Dember effect.

Epitaxial growth and interfaces of high-quality InN films grown on nitrided sapphire substrates

“…1,2 Moreover, InN has a direct band gap of ;0.7 eV which enables the III-nitride semiconductors to cover the wave length from deep ultraviolet (AlN, Eg 5 6.2 eV) to near infrared (InN, Eg 5 0.7 eV). 3,4 InN has shown great potential in the fields of terahertz emitters, [5][6][7][8] light-emitting 9 and photovoltaic applications, 10 etc. In 1972, Hovel and Cuomo 11 grew InN thin films on sapphire by using radio-frequency sputtering for the first time.…”

Investigation of valence-band splitting in InN by low-temperature photoreflectance spectroscopy

“…In the last decade, InN has received considerable attention due to the lowest effective mass, the highest mobility, and the highest saturation velocity of the group-III nitrides, 1) making it a high potential material for high-efficiency solar cells, 2) light-emitting devices, 3) and terahertz applications. 4,5) However, because of the crystalline quality, the electronic band structures of InN continue to be a subject of debate. In particular, the details of the valence bands are controversially discussed.…”

Photoreflectance Study of InN Films with In and N Polarities

“…nN is an important component of the group-III nitride system and has recently received considerable attention due to its lowest effective mass, highest mobility, and highest saturation velocity among the group-III nitrides, 1) making it a potential material for high-efficiency solar cells, 2) light-emitting diodes, 3) and terahertz applications. 4) A very significant issue for InN is the polarity of the InN surface, which affects its electrical and optical properties. Therefore, determining the polarity of InN is important.…”