The research presented herein focuses on electrical assessment of oxide thin films as insulators. The current density-electric field (J-E) characteristics of four insulators of dramatically different electrical quality are assessed in terms of their operative electronic conduction mechanisms. Conduction in the two high-quality insulators is dominated by Ohmic conduction and...
The trend towards higher resolution, faster refresh rate active-matrix liquid-crystal displays (AMLCDs) as well as the emergence of active-matrix organic light-emitting diode (AMOLED) displays is driving the demand for amorphous oxide semiconductor thin-film transistors (AOS TFTs) with higher mobility. A physics-based model for carrier transport in an amorphous semiconductor is...
The electrical stability of amorphous indium-gallium-zinc oxide (a-IGZO) thinfilmtransistors (TFTs) is investigated for flat-panel display applications. Althoughproducts incorporating a-IGZO TFT backplanes are already commercially available,e.g., iMac with 5K retina display, technical challenges need to be addressed for nextgenerationapplications, e.g., active-matrix organic light-emitting diode displays.Device stability is one crucial issue. The...
CIGS and CdTe based commercial thin-film solar cells (TFSCs) require an absorber thickness greater than 2 µm and 4 µm, respectively, to adequately absorb the solar spectrum. To efficiently extract photoexcited electrons, these TFSCs require relatively defect-free absorbers with high-minority carrier mobility (> 100 cm2V−1s−1) and long lifetime (> 10...
Due to a lack of grain boundaries, an amorphous metal thin film (AMTF) possesses advantageous mechanical properties and enhanced chemical stability that is potentially useful for thermal inkjet (TIJ) printing applications. The use of an AMTF as a TIJ resistor or cavitation plate could lead to a thinner TIJ cavitation...
The objective of the work reported herein is to explore the impact of decreasing channel thickness on radio-frequency (RF) sputtered amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) electrical performance through the evaluation of drain current versus gate voltage (I[subscript D] − V[subscript G]) transfer curves. For a fixed set of...
The aim of the research undertaken for this thesis was to develop a new high-performance amorphous oxide semiconductor (AOS) for use as a channel layer in a thin-film transistor (TFT). AOS TFTs offer higher electron mobility than the established amorphous silicon based technology. A new channel material comprised of aluminum...
The research presented herein represents an effort to combine the ultra-smooth surface of an amorphous metal thin film (AMTF) with a solution-processed dielectric synthesized via prompt inorganic condensation (PIC). Analysis of dielectric film quality is carried out via electrical measurements of metal-insulator-metal (MIM) diodes. Anneals at 500 and 700 °C...
Current cadmium telluride and copper indium gallium diselenide thin-film solar cells
(TFSCs) utilize thick absorbers (2 - 4 μm). For efficient carrier extraction in these TFSCs,
the absorber layer requires high carrier mobilities and a long minority carrier lifetime, which
necessitates the use of a high purity, defect-free thin film....
Amorphous metal thin films (AMTFs) are of potential use for metal-insulator-metal (MIM) tunnel diode applications due to their ultra-smooth surfaces, a consequence of their amorphous microstructure. The objective of this thesis is to design a thermally-stable AMTF capable of maintaining MIM tunnel diode performance after a post-deposition anneal in excess...
White electroluminescence (EL) was observed for the
first time from diamond-like carbon (DLC) films at room
temperature. Electroluminescence was observed by the
application of ac voltages in excess of 200 V to a metal-insulator-
semiconductor (i.e. DLC)-insulator-metal (MISIM)
device structure.
For EL applications, three types of the DLC films were...
The atomic solid state energy (SSE) scale is introduced as a tool for inorganic materials design. The SSE scale is obtained by assessing an average electron affinity (EA) (for a cation) or an average ionization potential (IP) (for an anion) for each atom using data from compounds having that specific...
The drain current of InP MISPETs is often observed
to decrease as a function of time after the application of
a positive gate bias which involves an accumulation of
electrons in the channel. Various models have been
proposed for this drain current drift (DCD) phenomenon.
In this thesis, variable-temperature bias-stress...
An analytical expression is derived which allows the
bulk minority carrier recombination lifetime, t, and the
surface recombination velocity, S, to be extracted from a
single noncontact photoconductivity decay (PCD) measurement. This analytical expression is rather complex, but
can be reduced to a first order approximation. The first
order approximation...
The stability of ZnS:Mn AC thin film Electroluminescence (ACEFEL)
devices as demonstrated by the brightness-voltage (BV)
characteristics is discussed. Two procedures for improvement of the
stability are demonstrated. The first method is the addition of a
CaS buffer layer to one or both interfaces of the ZnS active phosphor
layer....
A study of deep levels of the emitter region of a
heterojunction bipolar transistor is investigated using deep
level transient spectroscopy (DLTS), deep level admittance
spectroscopy (DLAS), thermally stimulated capacitance
(TSCAP), and capacitance-voltage (C-V) profiling. The DX
center, with an activation energy of 0.45 eV, is the only
deep level...
In this thesis the concept of inhomogeneous
dielectrics is demonstrated for various optical coating
applications. Compositionally-varying silicon oxynitride
(SiON) dielectric layers, with the refractive index
varying as a function of position, are grown by computer-controlled
plasma-enhanced chemical vapor deposition
(PECVD) using silane, nitrogen, and nitrous oxide reactant
gases. Compositionally graded...