MEMS BASED CZT RADIATION DETECTORS

BY: PRASHANT KUMAR
EEE-F6
15715604911

Contents
• Introduction
• Components of MEMS(Micro Electro-Mechanical
Systems)
• Materials for MEMS manufacturing
• MEMS basic processes
• Technologies for MEMS fabrication
• MEMS applications
• CZT detectors
• CZT detectors applications

Introduction
 MEMS is a technology that in its most general form can be defined as miniaturized
mechanical and electro-mechanical elements (i.e., devices and structures) that are made using
the techniques of micro-fabrication.
 The critical physical dimensions of MEMS devices can vary from one micron to several
millimeters.
 The types of MEMS devices can vary from relatively simple structures having no moving
elements, to extremely complex electromechanical systems with multiple moving elements
under the control of integrated microelectronics
3

COMPONENTS OF MEMS
 The functional elements of MEMS are
miniaturized structures, sensors,
actuators, and microelectronics.
 Micro-sensors and micro-actuators are
appropriately categorized as
“transducers”, which are defined as
devices that convert energy from one
form to another.
 Microelectronic integrated circuits can
be thought of as the "brains" of a
system.
 Microstructures means these
miniaturized sensors, actuators, and
structures can all be merged onto a
common silicon substrate along with
integrated circuits .
3

MATERIALS FOR MEMS MANUFACTURING
 SILICON
 POLYMERS
 METALS
 CERAMICS
4

MEMS BASIC PROCESSES
5
 DEPOSITION PROCESSES
 PHYSICAL DEPOSITION
 CHEMICAL DEPOSITION
 PATTERNING
 LITHOGRAPHY
 PHOTOLITHOGRAPHY
 ELECTRON BEAM LITHOGRAPHY
 ION BEAM LITHOGRAPHY
 X-RAY LITHOGRAPHY
 ETCHING PROCESSES
 WET ETCHING
 DRY ETCHING
 DIE PREPARATION

FABRICATING MEMS
6
 BULK MICROMACHINING:

7
 DEEP REACTIVE ION ETCHING
OF SILICON:
 DEEP REACTIVE ION ETCHING OF
GLASS :

 LIGA(LITHOGRAPHIE GALVANOFORMUNG ADFORMUNG):
8

MEMS APPLICATIONS
 BIOTECHNOLOGY
 MEDICINE
 COMMUNICATIONS
 INERTIAL SENSING
9

10
CZT (CADMIUM ZINC TELLURIDE)
 Cadmium zinc telluride, (CdZnTe) or CZT, is a compound of
cadmium, zinc and tellurium or, more strictly speaking, an alloy of
cadmium telluride and zinc telluride.
 The band gap varies from approximately 1.4 to 2.2 eV, depending on
composition.
 Cadmium Zinc Telluride (CZT),CdZnTe, is a semiconductor that
directly converts X-ray or Gamma-ray photons into electrons.
 It operates at room temperature and is capable of processing more
than one million photons per second per square millimeter.

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CZT DETECTORS
 The role of a gamma radiation
detector is to capture any gamma
ray photons which penetrate the
crystal and convert this energy
into electron-hole pairs that
migrate to the anode and cathode
at the top and bottom of the
crystal. The resulting electrical
signal is picked up at the
terminals of the device which are
connected to sensitive amplifiers
and analysis circuitry.
FIGURE 7.1: NORMALIZED COUNTS VS
ENERGY (KeV) GRAPH OF CZT

12
CZT DETECTORS APPLICATIONS
 Very high count rate at room temperature makes CZT an excellent
detector for medical, security, astrophysics, and industrial
measurement applications.
 Medical applications include bone density measurements, nuclear
medicine and probes for gamma-guided surgical procedures.
 Security system applications strive to detect and identify radiation
sources. Uses may be airport screening, first responders, or buildings
with restricted access to radioactive sources such as hospitals and
clinics.
 There are a variety of industrial measurement applications for the
food and beverage sector. These include the ability to accurately
sense the level of liquids or solids within closed containers where
optical inspection is not possible

MEMS BASED CZT RADIATION DETECTORS

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