In recent years, a new class of high-performance thin-film transistors (TFTs) has emerged comprising amorphous oxide channel materials composed of heavy-metal cations (HMCs) with (n-1)d¹⁰ns⁰ (n ≥ 4, where 'n' refers to the row of the periodic table) electronic configuration. This thesis is devoted to the fabrication and characterization of...
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....
The primary objective of this thesis is to explore new absorber and p-type window layer materials for thin-film solar cell applications. A new thin-film electron beam deposition system has been installed, is now operational, and has been used to deposit several types of solar cell absorber layers. Material investigations include...
This thesis focuses on two aspects of oxide-based thin-film transistors (TFTs), contact resistance and instability assessment.
First, determination of the contact resistance of indium tin oxide (ITO) on two wide-band gap semiconductors, zinc oxide (ZnO) and indium gallium oxide (IGO), is attempted and the effects of contact resistance on device...
Current leading thin-film solar cell technologies, i.e., cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS), employ elements which are either toxic (Cd), or rare and/or expensive (In, Te, Ga, and Cd). The aim of this thesis is to investigate new, abundant, non-toxic p-type semiconductors for potential solar absorber application....
The purpose of this thesis is to contribute to the understanding of SrS-based alternating-current thin-film electroluminescent (ACTFEL) device operation. Three main accomplishments serving this purpose are presented in this thesis. First, two new methods are developed for estimation of insulator capacitance in ACTFEL devices possessing a large amount of dynamic...
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...
This thesis focuses on two aspects of transparent electronics, SnO₂ transparent thin-film transistors (TTFTs) and transparent circuits. Both depletion- and enhancement-mode SnO₂ TTFTs are realized. The maximum effective mobility for the depletion- and enhancement-mode devices are 2 cm²V⁻¹s⁻¹ and 0.8 cm²V⁻¹s⁻¹, respectively. A variety of techniques to decrease the carrier...
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...