The fabrication of high quality superconducting thin films using pulsed laser deposition (PLD) has been reported to find optimized processing conditions and to make millimeter-wave devices.
A viable solution recently investigated towards this integration is the formation of a local substrate with the appropriate dielectric properties on the Si wafer, on which the RF and millimeter-wave devices will be integrated.
In order to demonstrate the high performance of porous Si for use as a substrate for RF and millimeter-wave devices, a comparison was made between this substrate and three other substrates used in the same respect.
In this work, the dielectric properties of porous Si for its use as a local substrate material for the integration on the Si wafer of millimeter-wave devices were investigated in the frequency range 140 to 210 GHz.
During the past decade, hexaferrite has become an important candidate for a variety of microwave and millimeter-wave devices due to their large uniaxial magneto-crystalline anisotropy and high saturation magnetization.
Among the new proposals for the use of magnetoelectric coupling phenomenon, the most spectacular and forward-looking ideas seem to be new-generation memories [15 17], spintronic devices (e.g., spin valves, magnetic tunnel junctions) [18 20], microwave, millimeter-wave devices and miniature antennas [14], and wireless medical tools (e.g., for endoscopy and brain imaging) [14].
This performance is added to the other advantages of PSi compared to other Si-based substrates, e.g., its compatibility with the low-resistivity CMOS substrate (permitting co-integration of CMOS logic with RF and millimeter-wave devices on the same substrate) and its low achievable permittivity).
In view of the application of porous Si for the on-chip integration of RF and millimeter-wave devices, its dielectric properties (dielectric permittivity and loss tangent) as a function of frequency should be known, in order to be used by the device designer for an accurate prediction of device operation.
As shown previously by the authors, the achieved low permittivity of porous Si at high porosities shows advantages in many RF and millimeter-wave devices, namely, high-characteristic impedance of the CPW TLines [5], inductors operating at higher frequencies [29, 30] and antennas with reduced surface waves induced into the substrate can be obtained.
"There are lingering questions about whether the millimeter-wave devices are retaining images," he said.
Therefore, they can be regarded as potential candidate materials for millimeter-wave device.
