PT Journal
AU Antipov, S
   Trifonov, A
   Krause, S
   Meledin, D
   Kaurova, N
   Rudzinski, M
   Desmaris, V
   Belitsky, V
   Goltsman, G
TI Improved bandwidth of a 2 THz hot-electron bolometer heterodyne mixer fabricated on sapphire with a GaN buffer layer
SO Supercond. Sci. Technol.
JI Supercond. Sci. Technol.
PY 2019
BP 075003
VL 32
IS 7
DI 10.1088/1361-6668/ab137b
DE NbN HEB mixer; GaN buffer layer; sapphire substrate
AB We report on the signal-to-noise and gain bandwidth of a niobium nitride (NbN) hot-electron bolometer (HEB) mixer at 2 THz fabricated on a sapphire substrate with a GaN buffer layer. Two mixers with different DC properties and geometrical dimensions were studied and they demonstrated very close bandwidth performance. The signal-to-noise bandwidth is increased to 8 GHz in comparison to the previous results, obtained without a buffer-layer. The data were taken in a quasi-optical system with the use of the signal-to-noise method, which is close to the signal levels used in actual astrophysical observations. We find an increase of the gain bandwidth to 5 GHz. The results indicate that prior results obtained on a substrate of crystalline GaN can also be obtained on a conventional sapphire substrate with a few micron MOCVD-deposited GaN buffer-layer.
ER