Optical Constants for MBE n-Type GaAs Films Doped by Si or Te between 1.50-4.75 eV

Svetlana N Svitasheva

doi:10.4236/jemaa.2010.26046

Abstract

The thickness and spectral dependence of the complex refractive index of upper layer in thin-film MBE-grown GaAs heterostructures were calculated basing on an classical oscillatory model of dielectric function from spectra measured by spectroscopic ellipsometry (nondestructive, contactless optical method) in the range of 1.5-4.75 eV.

Highlights

High-frequency (GHz) transistors and integrated circuits on the A3B5-type semiconductors are commonly used in mobile and satellite communication devices, and in on-board radar stations owing to their small weight and high efficiency
The thickness and spectral dependence of the complex refractive index of upper layer in thin-film MBE-grown GaAs heterostructures were calculated basing on a classical oscillatory model of dielectric function from spectra measured by spectroscopic ellipsometry in the range of 1.5-4.75 eV
Microwave transistors based on MBE-grown heterostructures have the best parameters

Summary

Introduction

High-frequency (GHz) transistors and integrated circuits on the A3B5-type semiconductors are commonly used in mobile and satellite communication devices, and in on-board radar stations owing to their small weight and high efficiency. Microwave transistors based on MBE-grown heterostructures have the best parameters. The active layer thickness is 0.15-0.30 μm and the doping level is within (1-5) × 1017 cm-3. The requirements imposed on an epitaxial layer can be formulated according to functional properties of a device (it is extremely difficult to satisfy them) [2]: 1) the buffer layer must contain the minimal number of shallow- and deep traps and ensure a spatially sharp barrier of a desired height for electrons in the channel; 2) homogeneity of thickness and doping level of the active layer must be high. At optimizing of the modes of growth of separate layers, for monitoring their parameters are usually used the following techniques: low-temperature photoluminescence, Hall, and C-V measurements. We suggest to pay attention to application of spectroscopic ellipsometry between 1.50-4.75 eV for restoration of thicknesses and optical constants of layers included into heterostructure (Figure 1)

Substantiation

The Goal of Paper

Experiment

Solving the Inverse Problem Ellipsometry

Results and Discussion

Conclusions