Mehdi Pakmehr

THz Hot-Electron Micro-Bolometer Based on Low-Mobility 2-DEG in GaN Heterostructure

We present the results on design, fabrication, and characterization of a hot-electron bolometer based on low-mobility 2-D electron gas (2-DEG) in an AlGaN/GaN heterostructure. The characterization of our hot-electron bolometers demonstrates that the following can be achieved simultaneously: 1) strong coupling to incident THz radiation due to strong Drude absorption; 2) significant THz heating of 2-DEG due to the small value of the electron heat capacity; and 3) high responsivity due to the strong temperature dependence of 2-DEG resistance. Low contact resistance achieved in our devices ensures that THz radiation couples primarily to the 2-DEG. Due to a small electron momentum relaxation time, the real part of the 2-DEG sensor impedance is ~50-100 Ω, which provides good impedance matching between sensors and antennas. The room temperature responsivity of our devices reaches ~0.04 A/W at 2.55 THz along with a noise equivalent power of ~5 nW/Hz1/2.

Electrical and terahertz magnetospectroscopy studies of laser-patterned micro- and nanostructures on InAs-based heterostructures

Nanostructures fabricated from narrow-gap semiconductors with strong spin-orbit interaction (SOI), such as InAs, can be used to filter momentum modes of electrons and offer the possibility to create and detect spin-polarized currents entirely by electric fields. Here, we present magnetotransport and THz magnetospectroscopy investigations of Hall-bars with back-gates made from in InGaAs/InAlAs quantum well structures with a strained 4 nm InAs inserted channel. The two-dimensional electron gas is at 53 nm depth and has a carrier density of about

THz Magneto-photoresponse of an InAs-based quantum point contact in the region of cyclotron resonance

6\times10^{11}

The g-factor of quasi-two-dimensional electrons in InAs/InGaAs/InAlAs inserted-channels

cm

Characterization of High Mobility InAs/InGaAs/InAlAs Composite Channels by THz Magneto-Photoresponse Spectroscopy

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Rashba Effect and Beating Patterns in the THz Magneto-Photoresponse of a HgTe-Based Two-Dimensional Electron Gas

and mobility of about

THz detectors based on heating of two-dimensional electron gas in disordered nitride heterostructures

2\times10^{5}

THz Magneto-Photoresponse Spectroscopy of Two-Dimensional Electrons in an InAs/InGaAs/InAlAs Inserted-Channel

cm

Investigating heat transport within CdZnSe substrate on quality of Bolometric effect of a HgTe/HgCdTe heterostructure

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Probing the effect of dopants (donors) within InAs/InGaAs/InAlAs Asymmetric Heterostructure wafer by magneto-THz spectroscopy

/Vs, after illumination. Electrical and THz optical transport measurements at low temperatures and in high magnetic fields reveal an effective mass of 0.038