By Topic

Electronic Structures Above Mobility Edges in Crystalline and Amorphous In-Ga-Zn-O: Percolation Conduction Examined by Analytical Model

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$33 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

3 Author(s)
Toshio Kamiya ; Mater. & Struct. Lab., Tokyo Inst. of Technol., Yokohama, Japan ; Kenji Nomura ; Hideo Hosono

Electronic structures and carrier transport mechanisms in disordered oxide semiconductors, crystalline InGaO3(ZnO)m (m = 1, 5) (c-IGZO) and amorphous InGaZnO4 (a-IGZO), are examined based on a percolation conduction model. Donor levels (E d) and densities (N D) are estimated by numerical calculations of free electron densities (n e) obtained by Hall measurements. It shows that the donor levels are rather deep, ~0.15 eV for c-IGZO and ~0.11 eV for a-IGZO. This analysis indicates that use of a simple analytical relation of ne prop exp(-Ed/2kT) can not always be used to estimate E d and N D even for a low n e film because the film can be in the saturation regime at room temperature if E d and N D are small, which is actually the case for a-IGZO. The temperature dependences of electron mobilities are analyzed using an analytical equation of the percolation conduction model, which reveals that distributed potential barriers exist above mobility edges in IGZO with average heights 30-100 meV and distribution widths 5-20 meV, which depend on atomic structure and deposition condition of IGZO films. High-quality a-IGZO films have the lowest potential barriers among the IGZO films examined, in spite that a-IGZO has a more disordered amorphous structure than c-IGZO have. It is explained by the partly disordered structure of c-IGZO.

Published in:

Journal of Display Technology  (Volume:5 ,  Issue: 12 )