TRANSPORT IN SILICON QUANTUM DOTS EMBEDDED IN A RARE EARTH OXIDE

Open Access
Author:
Aliyaru Kunju, Ashkar Ali
Graduate Program:
Engineering Science
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 31, 2009
Committee Members:
  • Suman Datta, Thesis Advisor
  • Osama O Awadelkarim, Thesis Advisor
Keywords:
  • Quantum dots
  • Device Physics
  • Transport
  • Capacitance-voltage
Abstract:
In this thesis, the room temperature quantum confinement effects in an array of Silicon (Si) quantum dots embedded in Gadolinium Oxide (Gd2O3) rare earth dielectric matrix is reported using photoluminescence (PL) spectroscopy. The high intensity and the small FWHM (0.12eV) of the PL peak indicate high crystalline quality and a narrow size distribution range (1 σ = 0.25nm) of the quantum dots. Electron storage density of 8x1012 cm-2 (corresponding to two electrons per quantum dot) is achieved by employing low programming voltage sweeps (-4V to 0V) as validated by the room temperature capacitance-voltage measurements. A temperature and field dependent study of the transport through the Si dot embedded Gd2O3 MOS tunnel diode structures is also presented. The tunneling mechanism assisted by the confined levels in the quantum dots and oxygen vacancy related trap level in the Gd2O3 dielectric is explained using physics based analytical models. The beneficial effect of forming gas anneal in controlling the trap density is also reported. This device has potential to be used in nanocrystal flash memory devices operating at low voltage. Better control of trap density and reducing the size of nanocrystal to about 3nm to allow only one energy level per dot could improve the performance of the device. It would be interesting to further study the Coulomb oscillations and the in-plane transport in coupled quantum dot array device. This could have potential applications for making single electron transistors at room temperature.