From Advanced Semiconductor Devices: Proceedings of The 2006 Lester Eastman Conference

Chapter List

Hybrid Nanomaterials for Multi-Spectral Infrared Photodetection
Ballistic Electron Acceleration Negative-Differantial-Conductivity Devices

ADRIENNE D. STIFF-ROBERTS
Department of Electrical and Computer Engineering, Duke University, Box 90291,
Durham, North Carolina 27708-0291, USA

adrienne.stiffroberts@duke. edu

Overview

Quantum dot infrared photodetectors (QDIPs) using quantum dots (QDs) grown by strained-layer epitaxy have demonstrated low dark current, multi-spectral response, high operating temperature, and infrared (IR) imaging. However, achieving near room-temperature, multi-spectral operation is a challenge due to randomness in QD properties. The ability to control dopant incorporation is important since charge carrier occupation influences dark current and IR spectral response. In this work, dopant incorporation is investigated in two classes of QDs; epitaxial InAs/GaAs QDs and CdSe colloidal QDs (CQDs) embedded in MEH-PPV conducting polymers. The long-term goal of this work is to combine these hybrid nanomaterials in a single device heterostructure to enable multi-spectral IR photodetection. Two important results towards this goal are discussed. First, by temperature-dependent dark current-voltage and polarization-dependent Fourier transform IR spectroscopy measurements in InAs/GaAs QDIPs featuring different doping schemes, we have provided experimental evidence for the important contribution of thermally-activated, defect-assisted, sequential resonant tunneling. Second, the enhanced quantum confinement and electron localization in the conduction band of CdSe/MEH-PPV nanocomposites enable intraband transitions in the mid-IR at room temperature. Further, by controlling the semiconductor substrate material, doping type, and doping level on which these nanocomposites are deposited, the intraband IR response can be tuned.

Keywords: Epitaxial quantum dots; colloidal quantum dots; hybrid nanocomposites, infrared photodetection.

1. Achieving Multi-Spectral Infrared Photodetection...

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Infrared (IR) spectrometers measure the wavelength and intensity of the absorption of infrared light by a sample.

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