Semiconductor Devices Physics and Technology

Semiconductor Devices

-Physics and Technology-

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Nano Hybrid Thin Films Lab

Outline

History of Thin Film Transistor

Band Structure

Carrier Transport Phenomena

Electrical Properties of Junction

Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) Junction Field Effect Transistor (JFET)

Thin-Film Transistors (TFTs)

Organic Thin-Film Transistors (OTFTs)

History of Thin Film Transistor

Nano Hybrid Thin Films Lab

History of Thin Film Transistor z The 1930s

History of Thin Film Transistor z The 1950s

History of Thin Film Transistor

z The 1960s

Control gate

Insulator

History of Thin Film Transistor

z The 1970s

?In 1979 a new material was introduced, with profound implication. LeComber, Spear, and Ghaith described a TFT using amorphous silicon as the active material.

Hydrogenated amorphous silicon

?It had previously been discovered that hydrogenated amorphous silicon, in contrast to pure amorphous silicon, could be doped with donors or acceptors to induce n-or p-type conductivity.?CdSe exhibits much higher mobilities than amorphous silicon, but CdSe is a polycrystalline compound; its properties are influenced by grain size, grain boundary interface states, stoichiometry, etc., and it can be sensitive to ambient gases such as H2O and oxygen. Amorphous silicon has no grain boundaries and is self-passivating.

Discharge Si3N4: dielectric layer

Discharge silicon : active layer

On current : several microamperes

OFF current : 1 nA

History of Thin Film Transistor z The 1980s

History of Thin Film Transistor z The 1980s

History of Thin Film Transistor

z The 1980s

SiNx passivation

Band Structure

Nano Hybrid Thin Films Lab

Relevance of Band Structure What is the electronic band Structure?

MO Diagram ReO

6

6-Octahetron

How dose this diagram change when we have an extended structure?

Band Structure ReO3

Band Structure (Hydrogen)

Band Structure (Hydrogen)

a : the lattice constant

(spacing between H atoms)

n : identification of the individual

atoms within the chain

Χn : the atomic orbitals

k : a quantum # that identifies the

wavefunction

?the phase of the orbitals

Band Structure (Hydrogen)

Band Structure (Hydrogen)

Band Structure : effect of orbital overlap

Band Structure : linear chain of F