Mohammadreza Kolahdouz

Improvement of infrared detection using Ge quantum dots multilayer structure

Monocrystalline SiGe/Si multiquantum dot and well structures have been manufactured/compared as thermistor materials for infrared detection. The performance of the devices (both the thermal and electrical) has been very sensitive to the quality of the epitaxial layers which is evaluated by the interfacial roughness and strain amount. This study demonstrates that the devices containing quantum dots have higher thermal coefficient resistance 3.4%/K with a noise constant (K1/f) value of 2×10−9.

Carbon-doped single-crystalline SiGe/Si thermistor with high temperature coefficient of resistance and low noise level

SiGe (C)/Si(C) multiquantum wells have been studied as a thermistor material for future bolometers. A thermistor material for uncooled Si-based thermal detectors with thermal coefficient of resista ...

Comprehensive Evaluation and Study of Pattern Dependency Behavior in Selective Epitaxial Growth of B-Doped SiGe Layers

The influence of chip layout and architecture on the pattern dependency of selective epitaxy of B-doped SiGe layers has been studied. The variations of Ge-, B-content, and growth rate have been investigated locally within a wafer and globally from wafer to wafer. The results are described by the gas depletion theory. Methods to control the variation of layer profile are suggested.

Pattern dependency in selective epitaxy of B-doped SiGe layers for advanced metal oxide semiconductor field effect transistors

This study presents investigations about the physical mechanisms, origin, and methods to control the pattern dependency in selective epitaxial growth of Si1-xGex (x=0.14-0.32) layers. It is shown ...

Kinetic Model of SiGe Selective Epitaxial Growth using RPCVD Technique

Recently, selective epitaxial growth (SEG) of B-doped SiGe layers has been used in recessed source/drain (S/D) of pMOSFETs. The uniaxial induced strain enhances the carrier mobility in the channel. In this work, a detailed model for SEG of SiGe has been developed to predict the growth rate and Ge content of layers in dichlorosilane(DCS)-based epitaxy using a reduced-pressure CVD reactor. The model considers each gas precursor contributions from the gas-phase and the surface. The gas flow and temperature distribution were simulated in the CVD reactor and the results were exerted as input parameters for Maxwell energy distribution. The diffusion of molecules from the gas boundaries was calculated by Fick’s law and Langmuir isotherm theory (in non-equilibrium case) was applied to analyze the surface. The pattern dependency of the selective growth was also modeled through an interaction theory between different subdivisions of the chips. Overall, a good agreement between the kinetic model and the experimental data were obtained.

Selective Growth of B- and C-Doped SiGe Layers in Unprocessed and Recessed Si Openings for p-type Metal-Oxide-Semiconductor Field-Effect Transistors Application

This work presents the pattern dependency of the selective epitaxial growth of boron- and carbon-doped SiGe layers in recessed and unprocessed openings. The layer profile is dependent on deposition ...

Strain balance approach for optimized signal-to-noise ratio in SiGe quantum well bolometers

This work presents thermal and electrical characterization of SiGe/Si multi-quantum wells (MQWs) with different layer profiles in complete bolometer structures. The thermal property of the bolometers was studied by measuring thermal coefficient of resistivity (TCR) through I–V curves for five temperatures (25, 40, 55, 80 and 100°C) and for four different pixel areas. The results show a strong dependency of TCR on the Si/SiGe layer thickness and the presence of dopant impurity in the MQW. The noise measurements of MQWs were performed carefully by eliminating all external contributions and the noise spectroscopy provided the noise characteristic parameters. The results demonstrate that the noise depends on the geometric size of the MQW and it increases with decreasing of the pixel area. The investigations show the noise level in the bolometer structures is sensitive to any dopant segregation from the contact layers.

Highly selective and responsive ultra-violet detection using an improved phototransistor

An ultra-violet (UV) phototransistor with 700x200 lm2 gate area decorated with vertically aligned Zinc Oxide (ZnO) nanorods to enhance UV responsivity is designed and manufactured. Spectral responsivity of the device was measured for wavelengths ranged from 200 to 1100 nm of the electromagnetic spectrum in different transistor working regions. The best responsivity was achieved at sub-threshold and very weak inversion region. In order to enhance UV range selectivity, oxygen plasma has been employed on the nanorods, and consequently, nearly 3-fold improvement in its relative sensitivity at 375 nm was achieved. The final manufactured phototransistor shows a highly selective response of 24 kA/W in the UV range.

Kinetic model of SiGe selective epitaxial growth using RPCVD technique

Recently, selective epitaxial growth (SEG) of B-doped SiGe layers has been used in recessed source/drain (S/D) of pMOSFETs. The uniaxial induced strain enhances the carrier mobility in the channel. ...

Selective Epitaxial Growth with Full Control of Pattern Dependency Behavior for pMOSFET Structures

This study presents a way to design chips to obtain uniform selective epitaxial growth of SiGe layers in p-type metal-oxide-semiconductor field-effect transistor (pMOSFET) structures. The pattern d ...