Semiconductors group

Abstract:

The motivation for this research is that the emission spectra using directly pumped laser diodes have not yet been found. We want to explore the luminescence properties of a co-doped laser material utilizing a diode laser as an optical pump. The research method used standard melt-quench and was stimulated by a laser diode (808 and 980 nm). The double doped of Nd³⁺- Er³⁺/Nd³⁺-Pr³⁺ ions with glasses system of lithium-fluorophosphate (LFP) had a strong band emission at 1056 nm, which transitioned at ⁴F_3/2 → ⁴I_11/2 and showed a drop in intensity from co-doping with Er³⁺ and Pr³⁺ ions. The fluorescence width at half maximum (FWHM) of the glasses is calculated to identify whether the sample may be used as a laser application. The FWHM values are found to be 22-28 nm. Decay time values were shown to decrease with increasing concentrations of Er³⁺ and Pr³⁺ ions and were used for energy transfer calculations. The Quantum Yields (QYs), efficiency in the transfer of energy and the possibility transfer energy were measured and calculated that confirm the possibility of energy transfer from Nd³⁺ to Er³⁺ and Pr³⁺ ions. Since, the emission spectrum at 1535 nm was found, this is a good reason for it to be used as an optical device.

Abstract:

Optical Pump Terahertz Probe (OPTP) spectroscopy is a well-established measurement technique with which charge-carrier dynamics of semiconductor nanowires (NW) can be extracted in a noncontact manner. Here in this work, we employ OPTP spectroscopy for measuring temperature-dependent photoconductivity spectra of 3D Dirac Cd 3 As 2 semi-metal nanowires, revealing a high Extrinsic carrier concentration of ∼2.0x1017cm−3 and ultrahigh carrier mobility of up to ∼13x103cm2V−1s−1 at a temperature of 5 K.

Abstract:

Topological insulator (TI) materials are emerging as novel materials for spintronic applications. Here, we demonstrate helicity-dependent THz emission from Dirac semi-metal Cd 3 As 2 nanowires and used scattering-type scanning optical microscopy (s-SNOM) to identify potential single nanowire candidates for device applications. The preliminary investigation data of a candidate nanowire shows a homogenous topography and constant dielectric function in the MIR range. Indicating high-quality crystalline growth ideal for topological characterization.