Transcript Transparent Electronics Seminar

Guided by
Miss. Shahida
Submitted by,
Sajas K.K.
Roll no: 18
S5 EC
Introduction
What is transparent electronics?
 In transparent electronics the usual opaque
semiconductor materials forming the basis for
electronic device fabrication is replaced with
transparent materials.

There are two technologies which preceded
and underlie transparent electronics:
1. Transparent Conducting Oxides (TCOs)
2. Thin Film Transistors (TFTs)
Transparent Conducting Oxides TCOs)

TCOs constitute an unusual class of materials
possessing two physical properties (generally
considered mutually exclusive):
1. High optical transparency. ( Eg>3.1eV)
2. High electrical conductivity.
Transparent electronic
devices
Transparent Passive devices
Transparent Active devices
Transparent Passive devices
 Transparent Thin Film Resistors
 Transparent Thin Film Capacitors
 Transparent Thin Film Inductors
Transparent Thin Film Resistors
Resistive material: ITO (Indium Tin Oxide)
Typical sheet resistance ~ 10-105
Conductivity of TCO’s depends on number of
oxygen vacancies (𝑉𝑂 ) and metal atoms
occupying interstitial sites.
Transparent Thin Film Capacitors
 Most insulators are transparent.
 Contact layer is made of highly conducting
TCOs (ITO).
𝐶 = 𝜀𝑑𝑖𝐴 .
Transparent Thin Film Inductors
 Hard to realize due to poor conductivity of
TCO’s compared to metals. 𝑄 = 2𝜋𝑓𝐿/𝑅𝐿
 High L requires larger number of turns which
in turn results in increased parasitic resistance.
Schottky Barriers
Formed from metal (anode)-semiconductor
(cathode) junction.
Space charge region (depletion region) and
potential barrier formation due to difference in
work function of metal and semiconductor.
Schottky barrier height ∅𝐵𝑛 = ∅𝑀 − 𝜒𝑆
, where 𝜙𝐵𝑛 →Schottky barrier height
∅𝑀 →work function of metal
𝜒𝑆 →Electron affinity of semiconductor
Energy band in a Schottky barrier
Transparent Thin Film Transistors
Constitutes the heart of transparent
electronics
Channel is formed from highly insulating, wide
band gap transparent semiconductor(ZnO).
Source, drain and gate contacts are made
from highly conductive TCO (ITO).
Two possible configurations are:
a) Bottom gate
b) Top gate
Possible structure, (a) Bottom gate, and
(b) Top gate.
Operation of a bottom gate TFT
Strengths and Weaknesses
Strengths
Weaknesses
Visible transparency
High resistance of TCO’s
Large area
Lack of complementary devices
Low cost (solution based
deposition and printing)
Low frequency of operation.(KHz
to few MHz).
fT=𝜇(𝑉𝐺𝑆 − 𝑉𝑇 )/2𝜋𝐿2
Technological immaturity
Low temperature processing
Free real estate
Passive availability (R & C)
Robust stable inorganic materials
Safe, nontoxic materials
Applications
Active Matrix LCD (AMLCD).
Active Matrix Organic Light Emitting Device
display backplane (AMOLED).
Value added glass.
Transparent electronics on opaque substrates.
UV detectors and arrays
• Transparent solar cells
• UV detectors for spectrally resolved imaging.
• Security applications:
Invisible cameras and
Invisible RFID’s
Conclusion
• Started as a mere electrical device technology
during world war 2, transparent electronics
now holds the key for many future
advancements in security, entertainment
efficient utilization of energy.
Reference
• ‘Transparent Electronics ’, Springer
publications, J.F.Wager, D. A. Keszler, R. E.
Presley.
• ‘Transparent electronics: from synthesis to
applications’, Wiley publications: Antonio
Facchetti, Tobin J. Marks