Elastic Electron Scattering in InSb‐Type Semiconductors

Abstract

Relaxation times for elastic electron scattering in 111-V compounds of InSb type are calculated taking into account consistently the nonparabolic structure of the conduction band, both in the density of states and electron wave functions. The calculations are based on the Kane model of band structure, including explicitly mixing of p-like components into the total wave function of the conduction band. Electron scattering by charged impurities and heavy holes, optical phonons (polar interaction), acoustic phonons, and piezo-acoustic modes are considered. Screening by free electrons is included in the longrange interactions and shown to play an important role a t higher electron concentrations. Both spin-conserving and spin-flip transitions are considered for all modes. It is demonstrated that transverse branches participate appreciably in acoustic scattering at high electron energies. In all cases, the presented calculations give much higher values of the theoretical mobilities for heavily doped samples than those obtained up to now taking into account only the proper density of states.Die Relaxationszeiten fur elastische Elektronenstreuung in 111-V-Verbindungen vom InSb-Typ werden unter konsistenter Beriicksichtigung der nichtparabolischen Struktur des Leitungsbandes sowohl in der Zustandsdichte als auch in der Wellenfunktion berechnet. Die Berechnungen beruhen auf dem Kaneschen Bandstrukturmodell, wobei explizit die Zumischung von p-artigen Komponenten in die Gesamtwellenfunktion des Leitungsbandes eingeschloasen wird. Elektronenstreuung durch geladene Defekte und schwere Locher, optische Phononen (polare Wechselwirkung), akustische Phononen und piezo-akustische Moden werden beriicksichtigt. In den langreichweitigen Wechselwirkungen wird Abschirmung durch freie Elektronen eingeschlossen und gezeigt, daI3 sie eine bedeutende Rolle bei hoheren Elektronenkonzentrationen spielen. Es werden sowohl spin-erhaltende als auch spin-flipUbergiinge fur alle Moden beriicksichtigt. Es wird gezeigt, daB transversale Zweige einen betriichtlichen Anteil an der akustischen Streuung bei hohen Elektronenenergien haben. I n allen Fsllen ergeben die dargelegten Berechnungen vie1 hohere Werte der theoretischen Beweglichkeiten fur stark dotierte Proben als die bisher erhaltenen, die nur die richtige Zustandsdichte beriicksichtigen.

Dopants and defects in InN and InGaN alloys

“…We have used Hall effect measurements of electron transport properties and optical absorption measurements to demonstrate that energetic particle irradiation is a reliable method for controlling electrical and optical properties of In 1-x Ga x N. This control extends to InN films doped with Mg above a threshold radiation dose (~10 15 MeV/g). Energetic particle irradiation is an n-type doping method in InN and In-rich InGaN, but forms compensating acceptor defects in n-type GaN, due to the location of E FS relative to the conduction band edge.…”

“…The increase in electron concentration is approximately linear with dose for each type of particle, and thus irradiation provides a method for controlled n-type doping of InN over a wide concentration range. For D d of 5.9x10 15 MeV/g and higher, however, the electron concentration saturates at roughly 4x10 20 cm -3 .…”

“…The resulting equation for electron mobility limited only by ionized center scattering is derived from the work of Zawadzki and Szymanska on InSb, another narrow gap semiconductor [15]. It is given by:…”

“…where χ 0 is the static dielectric constant, Z is the charge of the ionized defect centers, N i is the concentration of ionized (defect) centers, and F i is a function that takes into account free electron screening effects and the reduction of the scattering rates that result from the mixed nature of the conduction band wavefunctions [15]. We averaged this energy-dependent electron mobility (µ i )…”

Electronic and Optical Properties of Energetic Particle-Irradiated In-rich InGaN

“…The initial free electron concentrations in these samples range from the low 10 18 cm -3 to low 10 17 cm -3 and the mobility ranged from 7 cm 2 /V·s (x = 0.76) to above 1500 cm 2 /Vs (x = 0). In addition, a GaN sample (3 µm thick with an electron concentration ~7.74×10 17 In all cases, the particle penetration depth greatly exceeded the film thickness, assuring a homogeneous damage distribution in the film. Ion channeling spectroscopy showed that the minimum yield χ increased from 0.04 in an as-grown InN sample to merely 0.11 after 4 He + irradiation with a dose of 1.8×10 16 cm -2 , indicating that the InN films remains single crystalline in spite of the high concentration of radiation-induced defects.…”