Thermal field controlled electrical conductivity change devices and applications therefore are provided. In some embodiments, a thermal switch, comprises: a metal-insulator-transition (MIT) material; first and second terminals electrically coupled to the MIT material; and a heater disposed near the MIT material.

A metasurface unit cell for use in constructing a metasurface array is provided. The unit cell may include a ground plane layer comprising a first conductive material, and a phase change material layer operably coupled to the ground plane layer. The phase change material layer may include a phase change material configured to transition between an amorphous phase and a crystalline phase in response to a stimulus. The unit cell may further include a patterned element disposed adjacent to the phase change material layer and includes a second conductive material. In response to the phase change material transitioning from a first phase to a second phase, the metasurface unit cell may resonate to generate an electromagnetic signal having a defined wavelength. The first phase may be the amorphous phase or the crystalline phase and the second phase may be the other of the amorphous phase or the crystalline phase.

A radio frequency (RF) switch includes a heating element, a nugget, a phase-change material (PCM), and input/output contacts. The nugget comprises thermally conductive and electrically insulating material, and is situated on top of the heating element. The PCM has an active segment approximately situated over the nugget, and passive segments approximately situated under the input/output contacts. The PCM RF switch may include thermally resistive material adjacent to first and second sides of the heating element, and/or adjacent to first and second sides of the nugget. The PCM RF switch may include a heat valve under the heating element.

In fabricating a semiconductor device, a shared material is formed in a resonator region of the semiconductor device and in a phase-change material (PCM) switch region of the semiconductor device. A portion of the shared material is removed to concurrently form a heat spreader comprising the shared material in the PCM switch region and a piezoelectric segment comprising the shared material in the resonator region. The piezoelectric segment in the resonator region and the heat spreader in the PCM switch region are situated at substantially the same level in the semiconductor device. The PCM switch region includes a heating element between the heat spreader and a PCM. The resonator region includes the piezoelectric segment between two electrodes.

A rapid testing read out integrated circuit (ROIC) includes phase-change material (PCM) radio frequency (RF) switches residing on an application specific integrated circuit (ASIC). Each PCM RF switch includes a PCM and a heating element transverse to the PCM. The ASIC is configured to provide amorphizing and crystallizing electrical pulses to a selected heating element in a selected PCM RF switch. The ASIC is also configured to generate data for determining and characterizing resistivity change of the selected heating element in the selected PCM RF switch after the ASIC performs a plurality of OFF/ON cycles. In one implementation, a testing method using the ASIC is disclosed.

A radio frequency (RF) switch includes a phase-change material (PCM) and a heating element underlying an active segment of the PCM, the PCM and heating element being situated over a substrate. A contact dielectric is over the PCM. PCM contacts have upper portions and uniform plate slot lower portions. The uniform plate slot lower portions have a total plate resistance R.sub.PLATE, and a total plate slot interface resistance R.sub.PLATE-INT. The upper portions have a total capacitance C.sub.UPPER to the uniform plate slot lower portions, and the PCM has a total capacitance C.sub.PCM to the substrate. The uniform plate slot lower portions significantly reduce a product of (R.sub.PLATE+R.sub.PLATE-INT) and (C.sub.UPPER+C.sub.PCM). As an alternative to the uniform plate slot lower portions, PCM contacts have segmented lower portions. The segmented lower portions significantly reduce C.sub.UPPER.

A rapid testing read out integrated circuit (ROIC) includes phase-change material (PCM) radio frequency (RF) switches residing on an application specific integrated circuit (ASIC). Each PCM RF switch includes a PCM and a heating element transverse to the PCM. The ASIC is configured to provide amorphizing and crystallizing electrical pulses to a selected PCM RF switch. The ASIC is also configured to generate data for determining and characterizing OFF state conductivity skew and ON state conductivity skew of the PCM in the selected PCM RF switch after the ASIC performs a plurality of OFF/ON cycles. In one implementation, a testing method using the ASIC is disclosed.

Electrically tunable metasurfaces including an array of subwavelength metasurface unit elements are presented. The unit elements include a stacked metal-insulator-metal structure within which an active phase change layer is included. A purely insulator, metal, or coexisting metal-insulator phase of the active layer can be electrically controlled to tune an amplitude and phase response of the metasurfaces. In combination with the subwavelengths dimensions of the unit elements, the phase and amplitude response can be controlled in a range from optical wavelengths to millimeter wavelength of incident light. Electrical control of the unit elements can be provided via resistive heating produced by flow of current though a top metal layer of the unit elements. Alternatively, electrical control of the unit elements can be provided via electrical field effect produced by applying a voltage differential between the top and bottom metal layers of the unit elements.

A radio frequency (RF) switch includes a phase-change material (PCM) and a heating element underlying an active segment of the PCM, the PCM and heating element being situated over a substrate. A contact dielectric is over the PCM. PCM contacts have upper portions and uniform plate slot lower portions. The uniform plate slot lower portions have a total plate resistance R.sub.PLATE, and a total plate slot interface resistance R.sub.PLATE-INT. The upper portions have a total capacitance C.sub.UPPER to the uniform plate slot lower portions, and the PCM has a total capacitance C.sub.PCM to the substrate. The uniform plate slot lower portions significantly reduce a product of (R.sub.PLATE+R.sub.PLATE-INT) and (C.sub.UPPER+C.sub.PCM). As an alternative to the uniform plate slot lower portions, PCM contacts have segmented lower portions. The segmented lower portions significantly reduce C.sub.UPPER.

In fabricating a radio frequency (RF) switch, a phase-change material (PCM) and a heating element, underlying an active segment of the PCM and extending outward and transverse to the PCM, are provided. Lower portions of PCM contacts for connection to passive segments of the PCM are formed, wherein the passive segments extend outward and are transverse to the heating element. Upper portions of the PCM contacts are formed from a lower interconnect metal. Heating element contacts are formed cross-wise to the PCM contacts. The heating element contacts can comprise a top interconnect metal directly connecting with terminal segments of the heating element. The heating element contacts can comprise a top interconnect metal and intermediate metal segments for connecting with the terminal segments of the heating element.