GeTe Nano Relay Actuation Through Reversible Phase Expansion
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Solution Overview
Problem
Existing semiconductor-based materials for micro/nanoscale actuators, such as vanadium oxide and Germanium Telluride, face limitations in achieving high work density and stability during phase transitions, particularly in MEMS/NEMS relays and micro/nano robotics.
Innovation Solution
Utilizing Germanium Telluride (GeTe) as a phase change material that undergoes reversible volumetric changes between crystalline and amorphous phases, enabling the fabrication of non-volatile micro/nanoscale actuators and relays by controlling phase transitions through heating and quenching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If phase change materials are used for high work density actuators, then actuator work density is improved, but material stability during phase transitions deteriorates
Solution Approach 1:
The patent changes the physical-chemical parameters of the phase change material by doping GeTe with sulfur and selenium, adjusting the composition to Ge1-xSiyTe1-y to achieve both high work density and improved stability during phase transitions
Solution Approach 2:
The patent creates a composite phase change material by combining GeTe with sulfur and selenium dopants, forming a multi-component system that leverages the beneficial properties of each element to achieve both high work density and operational stability
2Volume of moving object
If GeTe undergoes phase transition from crystalline to amorphous, then volumetric change is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent employs periodic thermal cycling with precisely controlled heating and cooling phases to induce reversible phase transitions, using pulsed heating to melt and quench the material into amorphous phase, then controlled heating to recrystallize it
Solution Approach 2:
The patent incorporates feedback control through resistance measurements and optical detection to monitor the phase state of GeTe in real-time, adjusting heating parameters to achieve precise control over the phase transition process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
GeTe actuators exhibit significant volumetric changes (up to 10%) and stability at room temperature, facilitating reliable actuation and non-volatile operation in MEMS/NEMS devices, including the fabrication of phase change nano relays.
Implementation Method 1
GeTe is a phase change material that can be transitioned from a crystalline phase to an amorphous phase upon when heated to −1000° K (sufficient to melt the material) and quickly quenched
Implementation Method 2
heated to −1000° K (sufficient to melt the material) and quickly quenched
Implementation Method 3
The transition to the amorphous phase results in a volumetric increase of about 10%
Implementation Method 4
the material undergoes a transition from an amorphous phase to a crystalline phase upon heating to −500° K, resulting in a decrease in volume of the material
Implementation Method 5
the material undergoes a transition from an amorphous phase to a crystalline phase upon heating to −500° K
Implementation Method 6
The device is switched by pulses through heater 102
Implementation Method 7
One heater electrode 106 is held at ground while square voltage pulses or another voltage waveform is applied to the other electrode 108
Implementation Method 8
The device 100 is switched by pulses through heater 102. PCM 104 is converted to the amorphous (volumetrically larger) state by melting and quenching the material
Data Source
AI summary
A MEMS/NEMS actuator based on a phase change material is described in which the volumetric change observed when the phase change material changes from a crystalline phase to an amorphous phase is used to effectuate motion in the device. The phase change material may be changed from crystalline phase to amorphous phase by heating with a heater or by passing current directly through the phase change material, and thereafter quenched quickly by dissipating heat into a substrate. The phase change material may be changed from the amorphous phase to a crystalline phase by heating at a lower temperature. An application of the actuator is described to fabricate a phase change nano relay in which the volumetric expansion of the actuator is used to push a contact across an airgap to bring it into contact with a source/drain.