Hot electron–hole plasma dynamics and amplified spontaneous emission in ZnTe nanowires

Abstract

Key to optimizing and tailoring the optoelectronic properties of semiconductor nanostructures for practical applications is a clear understanding of their carrier interactions and recombination dynamics. Herein, the electron-hole (e-h) plasma dynamics and the electron-phonon coupling interactions in zincblende ZnTe nanowires (NWs) were systematically investigated by time-resolved photoluminescence (TRPL) spectroscopy over a wide range of lattice temperatures (4-300 K) and pump densities. Following intense, non-resonant femtosecond (fs) laser pulse excitation, the excited carriers thermalize to quasi-equilibrium distribution through carrier-carrier and carrier-phonon scattering within a few picoseconds. The peak temperature of the hot electron gas (T) is much higher than the lattice temperature and increases sub-linearly with the pump fluence. The hot electron gas thermalizes in two characteristic carrier density-dependent regimes - i.e., within 35 ps under high carrier densities (e-h plasma) while persisting to 360 ps under low carrier densities (exciton). Temperature-dependent studies of the ZnTe NWs revealed that the acoustic phonons play a significant role in the cooling of the hot e-h plasma in these NWs and the emission band broadening arises from the interplay of the contributions from crystal imperfections, LA and LO phonon scattering and most importantly, from the hot carrier thermalization. For demonstration, e-h plasma-amplified spontaneous emission in ZnTe NWs at room temperature by one- and two-photon excitation was realized. The results provide new insights into carrier interactions and recombination dynamics of ZnTe NWs and highlight their potential for high-efficiency e-h plasma light emitters, sensors and in plasma photochemotherapy.

Electron–Hole Plasma Lasing Dynamics in CsPbClmBr3-m Microplate Lasers

“…This is caused by the formation of an EHP being the underlying gain process during the lasing in our WGM microplate cavity, as reported for many other semiconductor nanostructures. 28,30,44,45 The competition of these resonant modes is visible in Figure 4b, accompanied by redshifts of the entire gain profile, which suggests the increase of bandgap renormalization (BGR) with elevated carrier density and provides a further signature of the existence of EHP 46,47 in the CsPbCl 3 microplate. The BGR is caused by the many-body effect 27 at high carrier densities.…”

Simulation of temperature profile for the electron and the lattice systems in laterally structured layered conductors

“…In small devices on nanoscales, hot electron generation and the resulting characteristic in-teraction with the host crystal lattice (or phonons) complicates the electro-thermal analysis and limits the device performance [16,17]. Whereas knowing the detailed local profile of the electron effective temperature, T e , separately from that of the lattice temperature, T L , in the presence of current is prerequisite for understanding the transp-1 port characteristics on nanoscales [18][19][20][21][22],T e has been experimentally hardly accessible [23][24][25][26][27][28][29][30][31] until quite recently [32,33]. It follows that the study of electro-thermal properties has so far been restricted only to the simulation methods such as those of Monte Carlo (MC) simulation based on the Boltzmann transport equations, hydrodynamic equations or molecular dynamics [34][35][36][37][38].…”

“…the transport characteristics on nanoscales [18][19][20][21][22], T e has been experimentally hardly accessible [23][24][25][26][27][28][29][30][31] until quite recently [32,33]. It follows that the study of electro-thermal properties has so far been restricted only to the simulation methods such as those of the Monte Carlo (MC) simulation based on the Boltzmann transport equations, hydrodynamic equations or molecular dynamics [34][35][36][37][38].…”

Charge Carrier Dynamics and Broad Wavelength Tunable Amplified Spontaneous Emission in ZnxCd1–xSe Nanowires

“…Semiconducting NWs exhibit promising applications as excellent gain materials because they can provide good geometric uniformity, tight photon confinement, and low scattering loss for highly localized coherent output and efficient waveguiding. − Numerous studies of NW lasers with a broad and tunable amplified spontaneous emission (ASE)/lasing emission wavelength range of 375–1550 nm have been focused on the perovskite and III–V and II–VI semiconductor compounds. − As a typical II–VI semiconductor, CdSe-ZnSe has been extensively studied because of the excellent optical and electronic properties for light-emitting diodes and laser materials in the visible range. − CdSe is of obvious nonlinear optical properties with the direct band gap (1.74 eV) for room-temperature lasers and electroluminescence . ZnSe is also a good candidate for room-temperature lasing with a direct band gap (2.69 eV) .…”