^{1}, S. P. Purohit

^{1,a)}and K. C. Mathur

^{1}

### Abstract

In this paper we study the linear and nonlinear intersubband optical properties of a nanocrystalline singly charged Si semiconductor quantum dot surrounded by an amorphous matrix of silicon dioxide, silicon nitride, and siliconcarbide. A finite barrier height is considered at the interface of the dot and matrix. We also consider the effect of self-energy associated with the surface polarization due to the charging of the dot and the size dependent dielectric constant of the dot. The effect of the surrounding matrix is investigated on the linear and nonlinear absorption coefficient,refractive index changes, nonlinear susceptibility, and photoelectric cross section. Using the effective mass approximation (EMA) results are obtained for different dot radii, photon energies, and intensities. It is noted that an increase in barrier height due to the surrounding matrix leads to blueshift in peak positions of absorption coefficients and refractive index change.

We thank the Jaypee Institute of Information Technology, Noida for providing the facilities and support to carry out this work.

I. INTRODUCTION

II. THEORY

A. Photoabsorption process

B. Refractive index change

C. Photoelectric process

III. RESULTS AND DISCUSSION

IV. CONCLUSIONS

### Key Topics

- Quantum dots
- 35.0
- Refractive index
- 30.0
- Carbides
- 19.0
- Optical properties
- 16.0
- Silicon
- 14.0

## Figures

The variation of the energy difference of the excited (1p) and the ground (1s) states as a function of dot radius.

The variation of the energy difference of the excited (1p) and the ground (1s) states as a function of dot radius.

The variation of linear, nonlinear, and total photoabsorption coefficient as a function of the incident photon energy at intensity *I* = 1.0 × 10^{11} W/m^{2} and dot radius *R* = 28 Å.

The variation of linear, nonlinear, and total photoabsorption coefficient as a function of the incident photon energy at intensity *I* = 1.0 × 10^{11} W/m^{2} and dot radius *R* = 28 Å.

The variation of the total photoabsorption coefficient as a function of photon energy at different values of the dot radii and intensity *I* = 1.0 × 10^{11} W/m^{2}.

The variation of the total photoabsorption coefficient as a function of photon energy at different values of the dot radii and intensity *I* = 1.0 × 10^{11} W/m^{2}.

The variation of the total photoabsorption coefficient as a function of photon energy at different values of intensities and dot radius *R* = 28 Å.

The variation of the total photoabsorption coefficient as a function of photon energy at different values of intensities and dot radius *R* = 28 Å.

The variation of linear, nonlinear, and total change in refractive index as a function of the incident photon energy at intensity *I* = 1.0 × 10^{11} W/m^{2} and dot radius *R* = 28 Å.

The variation of linear, nonlinear, and total change in refractive index as a function of the incident photon energy at intensity *I* = 1.0 × 10^{11} W/m^{2} and dot radius *R* = 28 Å.

The variation of total change in refractive index as a function of the incident photon energy at different values of dot radii and intensity *I* = 1.0 × 10^{11} W/m^{2}.

The variation of total change in refractive index as a function of the incident photon energy at different values of dot radii and intensity *I* = 1.0 × 10^{11} W/m^{2}.

The variation of total change in refractive index as a function of the incident photon energy at different values of intensities and dot radius *R* = 28 Å.

The variation of total change in refractive index as a function of the incident photon energy at different values of intensities and dot radius *R* = 28 Å.

The variation of third order optical susceptibility as a function of the incident photon energy at different values of intensities and dot radius *R* = 28 Å.

The variation of third order optical susceptibility as a function of the incident photon energy at different values of intensities and dot radius *R* = 28 Å.

The variation of the total photoelectric cross section from the 1s state as a function of incident photon energy.

The variation of the total photoelectric cross section from the 1s state as a function of incident photon energy.

The variation of the (a) absorption coefficient, (b) change in refractive index, and (c) nonlinear susceptibility as a function of the incident photon energy at intensity *I* = 1.0 × 10^{11} W/m^{2} and dot radius *R* = 28 Å without the local field factor.

The variation of the (a) absorption coefficient, (b) change in refractive index, and (c) nonlinear susceptibility as a function of the incident photon energy at intensity *I* = 1.0 × 10^{11} W/m^{2} and dot radius *R* = 28 Å without the local field factor.

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