Electron-Optical-Phonon Scattering Rate In A Strained GaN/Ga_xIn_1-xN Heterojunction

In this thesis, the dielectric continuum model and Fermi golden rule are adoptedto investigate the electron-phonon scattering rates via the four branches of opticalphonon modes in a strained zinc-blende heterojunction by considering of the effectsof lattice strain on phonon frequencies, dielectric constants, energy band gap andelectronic band mass, respectively.The numerical computation is performed for the variations of material constantswith lattice strain in GaN/Ga_xIn_1-xN heterojunction by considering the realisticheterojunction potential. The result showed that the strain effects on the frequency ofbulk phonons, static dielectric constants, energy band gap and electronic band massin the heterojunction are obvious, whereas the effects on the optical dielectricconstants and frequency of interface phonons are negligible.Furthermore, using the ground state wave function obtained by a variationalmethod, the influence of lattice strain on the electron-phonon scattering rates ofphonons in GaN/Ga_xIn_1-xN heterojunction is discussed by considering the contribution of bulk longitudinal optical(LO) phonon modes of two componentmaterials and two branches of interface optical(IO) phonon modes. It is found that thebulk LO phonon in the channel side of the heterostructure plays a main role to thetotal scattering rate. The influence of lattice strain on the total scattering rate ofphonons is obvious when the process of a phonon absorbed by electron is onlyconsidered, but unobvious when both absorbing and emitting phonon process areconsidered. The electron-phonon scattering rates as a function of electronic energy atdifferent areal electron density were also calculated. The result indicates that the totalscattering rate in the heterojunction increase with the areal electron density due to thecontribution from IO phonons.