Losses in diamond in the millimeter range

Dielectric losses in CVD diamonds in the millimeter-wave range at temperatures 300?900 K

“…The band gap in diamond is much wider than in silicon and is very large (5.6 eV). Therefore, in contrast to Si:Au, the lowest losses observed in CVD diamonds significantly exceed the lowest theoretical limit tan δ ≤ 3 · 10 −8 [3,8,11,12,20] determined by the two-phonon intrinsic lattice losses in the corresponding perfect crystal. This also follows from the comparison performed in [14,15] between the temperature dependence of losses in the best CVD-diamond sample and the theoretical dependence of the intrinsic lattice losses, whence the upper estimate tan δ < 7 · 10 −7 was found for the intrinsic lattice losses in diamond at a frequency of about 150 GHz at room temperature [14,15].…”

“…In this respect, CVD diamonds remain insufficiently studied. In particular, the temperature dependences in the range 300-1000 K were previously studied only for a single experimental specimen [9,11,12]. In that case, a change in the temperature dependence of losses with frequency was not studied.…”

“…These losses are related to defects, impurities, and non-diamond inclusions, i.e., it is in principle possible to significantly decrease the losses by improving the growth technology. In this way, the lowest losses were reduced by 2 orders of magnitude during the last 10 years and continue to decrease [1,[4][5][6][7][8][9][10][11][12][13][14][15]. In the case of the further decrease in losses, it would be possible, e.g., to remove the water cooling system in windows for output and input of electromagnetic energy (see the above discussion), to significantly simplify their design, and thereby to enhance reliability of the entire facility.…”

“…In the latter, the lowest theoretical limit for this material at room temperature has been achieved. This limit is stipulated by conductivity due to free charge carriers in silicon [3,19]. The band gap in diamond is much wider than in silicon and is very large (5.6 eV).…”

“…Studying dielectric losses in polycrystalline diamonds grown by chemical vapor deposition (CVD) has become very topical in the millimeter-wave range because of considerable progress in the growth technology and the corresponding applications of this previously "exotic" material in modern engineering [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The grown diamond disks have a number of remarkable electrical and mechanical properties:…”