Polaronic effects in asymmetric quantum wire: An all-coupling variational approach

Abstract

An all-coupling variational calculation based on Lee-Low-Pines-Huybrechts (LLPH) theory is performed to study the ground state and the first excited state in an asymmetric polar semiconductor quantum wire that is valid for the entire range of the electron-phonon coupling constant and arbitrary confinement length. It is shown that the polaronic effects are very important and size dependent, if the effective width of the wire is reduced below a certain length scale. It is also shown that asymmetry in a quantum wire can be used as an extra parameter to increase the stability of the polaron. Finally the theory is applied to a realistic CdS quantum wire.

The influence of electric field on the interface polaron properties in a wurtzite nitride nanowire

“…[17,[21][22][23][24][25][26][27][28]). Degani and Hipólito [21] have calculated the polaron self-energy (PSE) and the effective mass (PEM) in the GaAs/GaAlAs QWR using a variational approach which is based on the canonical transformation method of Lee, Low and Pines (LLP) [29].…”

“…Xie [26] has considered a freestanding cylindrical QWR and obtained the PSE and correction to the electron effective mass due to electron-LO-phonon interaction and also electron-surface optical phonon interaction using the second-order perturbation theory and taking into account the contributions from higher energy subbands. Within the framework of Lee-Low-Pines-Huybrechts variational theory Krishna et al [27,28] have investigated the polaronic binding energies corresponding to the ground state and the first excited state of an electron in a polar quantum wire with parabolic confinement in the transverse direction and it has been shown that even the longitudinal PEM is strongly enhanced by the transverse confinement in a QWR. Recently, the ground state PSE and PEM due to the quasi-confined and surface optical phonon modes in a freestanding wurtzite GaN NW are studied by employing the second-order perturbation approach [17,30] and LLP variational approach [31].…”

Polaron effects on the binding energy of a hydrogenic impurity in parabolic quantum wires in perpendicular electric and magnetic fields

“…In the frame of the Rayleigh-Schrödinger perturbation theory, the polaron problem is discussed in a QWR made of a wurtzite-type material [7]. An all-coupling variational calculation based on the Lee-Low-Pines-Huybrechts theory is performed to study the polaron ground state and the first excited state in an asymmetric polar semiconductor QWR [8].…”

Binding energies of bound polaron in a wurtzite nitride nanowire: Contributions of IO and QC phonon modes

“…Since the pioneering experimental work of Fan's group 1 on the synthesis of the first wurtzite GaN nanorods, the quasi‐1‐dimensional (Q1D) GaN‐based nanowires (NWs) have attracted a considerable amount of attentions both in theoretical and experimental investigations 1–16. This is mainly due to the following three evident facts: the nitride materials (including GaN, AlN, InN, and their ternary compounds, AlGaN and InGaN) with strong atomic bonding and wide and adjustable direct‐bandgap, which make them quite potential as a basis for the creation of reliable high‐temperature and high‐frequency nano‐optoelectronic devices such as field‐effect‐transistors (FETs), high‐brightness blue/green light‐emitting diodes and laser diodes as well as photodetectors 2–5; Q1D structure' confinement of NWs for carriers in two dimensions and freedom in the last dimension, promising more efficient lasers and optical gain as well as possible applications for optical waveguide and photovoltaic elements in comparisons with quantum wells (QWs) and quantum dots (QDs) 6–10; the Q1D NW systems also playing an important role in testing and understanding fundamental concepts, such as the role of dimensionality and size in optical, electrical, and mechanical properties 11–16. Hence the investigation of electronic and optoelectronic properties in GaN‐based NWs has become a hot topic during the last decade for their concomitant advantages of possessing both excellent optoelectronic properties and nanoscale dimensions.…”