Abstract
A thermal actuator based on thin flexible lamellas of Ga2O3 was designed in order to demonstrate the potential of this semiconductor for micro-opto-electro-mechanical applications (MOEMs). The working principle of these devices is based on the thermal expansion that induces a vertical movement resultant of the lamella elongation due the self-heating/Joule effect. Upon excitation with photons, electrons or ions, intrinsic luminescence bands associated with self-trapped excitons and donor-acceptor pair recombination dominate the emission spectrum. When a current passes through the device, simultaneously with the thermal expansion, this luminescence is strongly quenched. Based on systematic Photoluminescence and Raman studies as a function of temperature and as a function of the applied power it is demonstrated that the observed luminescence quenching is directly related with the Joule heating effect. This work presents for the first time a thermal actuator based on Ga2O3 and it intends to be a stimulus for future works on MOEMs applications based on this semiconductor.
Highlights
The recent renewed interest in monoclinic β-Ga2O3 arises from its potential for transparent optoelectronic devices up to UV due to its wide bandgap of ∼4.9 eV.[1,2,3,4,5,6] the large breakdown voltage of ∼8 MV cm−1 is another property that makes this semiconductor a promising material for high power electronics.[7]
In order to assess the thermal expansion of the actuator, it was first necessary to establish the calibration of the beam temperature as a function of the applied electrical power
The focal distance was realigned to maximize the Raman signal in order to compensate the defocussing caused by the vertical movement of the crystal as the power is increased
Summary
The recent renewed interest in monoclinic β-Ga2O3 arises from its potential for transparent optoelectronic devices up to UV due to its wide bandgap of ∼4.9 eV.[1,2,3,4,5,6] the large breakdown voltage of ∼8 MV cm−1 is another property that makes this semiconductor a promising material for high power electronics.[7]. In order to assess the thermal expansion of the actuator, it was first necessary to establish the calibration of the beam temperature as a function of the applied electrical power (note that this calibration may be different for different devices due to the varying size of exfoliated crystals and due to the above mentioned variations in contact properties).
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