NbTiN Receiver Homepage
Employing a Twin-Slot Quasi-Optical Mixer

Last Updated May 5, 2001 by Jacob W. Kooi

Related Papers:
 J.W. Kooi, J.A. Stern, G. Chattopadhyay, H.G. LeDuc, B.Bumble, and J. Zuidzinas,
"Low Loss NbTiN Films for THz SIS Mixer Tuning Circuits" ,
Int J. IR and MM Waves,, Vol. 19, No. 3, March, 1998.

J. Zmuidzinas, J. W. Kooi, , J. Kawamura, G. Chattopadhyay, B. Bumble, H. G. LeDuc, and J. A. Stern,
"Development of SIS mixers for 1 THz",
Proc. SPIE, vol. 3357, pp. 53-61

J.A. Stern, B. Bumble, H.G. LeDuc, J.W. Kooi, J. Zmuidzinas,
"Fabrication and DC-Characterization of NbTiN Based SIS Mixers for the Use betwen 600 and 1200 GHz".
Ninth International Symposium on Space Terahertz Technology, Pasadena, California, March 1998.

2-D Computer Simulations

     Calculated Losses for microstrip thin-film transmission line at 4.2 K.
     The microstrip width is 5um and the SiO dielectric (Er=5.6) is 400 nm  

  • Microstrip line losses at 4.2K (52K).

         July 1997 mask with a full 2-Dimensional calculation of a NbTiN/MgO/NbTiN junction.
         The first number is the design frequency, the number in parenthesisis the actual 2_D simulated frequency.  

  • Circuit simulation with a full 2-D calculation of a NbTiN/MgO/NbTiN junction.

         July 1997 mask with a full 2-Dimensional calculation of a Nb/AlOx/Nbjunction.
         The first number is the design frequency, the number in parenthesis is the actual 2_D simulated frequency.  

  • Circuit simulation with a full 2-D calculation of a Nb/AlOx/Nb junction.

         Below we present a full 2-Dimensional calculation with an E-beam NbTiN/MgO/NbTiN 0.2um x 3.6um junction.
         From the above it is quite aparent that a square 0.8um x 0.8um junction is far from optimal.
         (Same size junction as in the above simulations).
          Note the tremendous improvement in coupling efficiency and center frequency, even at 1200 GHz!  

  • Circuit simulation with a full 2-D calculation E-beam NbTiN/MgO/NbTiN junction

    FTS and Heterodyne Measurements, Niobium-1996 mask, Vphase=0.30c

         NbTiN Groundplane, Nb Wiring, Nb/AlOx/Nb Junction, Batch-L970218  

  • Total Power and I/V curves at 639 GHz (7.7K).  
  • FTS response and pcircuit simulation fit, including fit parameters (52K)  
  • FTS response (6.9K)  
  • I-V curve picture, x-axis: 1mV/div

         NbTiN Groundplane and Wiring, Nb/AlOx/Nb Junction, Batch-970312  

  • Total Power and I/V curves at 630 GHz (7.6K).  
  • FTS response and pcircuit simulation fit, including fit parameters (48.7K)  
  • FTS response (6.5K)  
  • I-V curve picture, x-axis: 1mV/div. Note heat trapping.

         All NbTiN Device, MgO barrier. Batch-L970318  

  • Total Power and I/V curves at 492 GHz. J970701, Dev. 71 (7.9K).  
  • FTS response and pcircuit simulation fit Jc=4.2kA/cm^2, L970318 (46K)  
  • FTS response and pcircuit simulation fit Jc=6.4kA/cm^2, L970318 (46K)  
  • I-V curve picture, x-axis: 2mV/div

    FTS and Heterodyne Measurements, NbTiN-1997 mask, Vphase=0.21c

         All NbTiN Device, MgO barrier. Batch-L970701  

  • Total Power and I/V curves at 638 GHz. J970701, Dev. 71 (7.9K).  
  • FTS Reponse of J970701, device 71  
  • Picture of I/V curve from an all NbTiN device from run: j970825. Vgap > 5.2mV, x-axis: 2mv/div!

         All NbTiN Wiring and Ground plane, NbTiN/AlN/Nb junction. Batch-L970811  

  • Total Power and I/V curves at 582 GHz. J970811, 650 GHz device (7.9K).  
  • FTS Reponse of J970811, 650 GHz device

         NbTiN Wiring and Ground plane(with a 1nm Nb layer), Nb/AlN/Nb junction. Batch-J970826  

  • I/V curve at 792 GHz, devices switches under LO power
         resulting in a 13dB mixer conversion loss and 790K noise-temperature. (note Vgap=3.5 mV)  
  • FTS Reponse of a 950 GHz tuned, 0.8um^2 device. Low loss, High Q direct detection reponse

     
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    Web Page created and last updated on March 5, 2001, by: Jacob W. Kooi