WP s involved WP Wide IF-band (650 GHz)

Transcription

1 WP s involved WP Wide IF-band (650 GHz) Design study for wide IF-band mixer (1/1/2004) WP GHz 2-SB mixer Mixer design study and fabrication technology study (1/2/2004) WP Phonon-cooled HEB-mixer Implementation of twin slot antenna and performance testing (1/1/2004) WP Detectors for bolometers arrays Start-up of work on Kinetic Inductance Detectors (1/6/2004) Thin-film & device technology (Delft) Device physics (Delft) Delft University of Technology Design & RF evaluation (SRON ) Kavli Institute of Nanoscience

2 People involved Mathias Kroug Tony Zijlstra Niels Hovenier Chris Lodewijk Jian-rong Gao (SRON/TUD) Merlijn Hajenius (SRON/TUD) Xxx TMK

3 Quick overview Band 9

4 High Jc / submicron-size SIS junctions (details see.pdf file)

5 Intermediate process step

6 Junction resistance, batch / 02

7 Enhanced sensitivity through device development

8 TIME-FRAME 1/10/04 1 T st cartridge 1 2 nd -9 th cartridge T 1 EBL 1/3/05 T 2 T 3 NbTiN wiring HIFI experience AlN & NbTiN 31/12/05 30% improvement in sensitivity (sensitivity, bandwidth, high frequency, lower LO power) T 4 SSB, 2SB etc New microwave designs based on 1 st cartridge etc. It takes 6 to 9 months between design, technology-adjustments, fabrication, RF evaluation and informed feedback

9 Junctions based on Nb /AlN / NbTiN Trilayer

10 NbN Superconductor Hot Electron Bolometer Mixers I: Status TU Delft: process and physics SRON: RF design and test Sensitive heterodyne detector THz THz signal hot electrons R Electron-Phonon fast device Interface engineering (Delft/SRON) record sensitivity: 750 K at 1.9 and 950 K at 2.5 THz 6 GHz IF gain bandwidth (Twin slot)

11 NbN Superconductor Hot Electron Bolometer Mixers I: Status New contacts Au Antenna Au pad Additional NbTiN 3.5 nm NbN Based on 3.5 nm NbN film on Si with a T c of 9.7 K (Moscow) Cleaning contact pad interface (clean NbN surface) Adding superconductor NbTiN (10 nm, T c =7-10 K) Baselmans et al, APL, 2004 Hajenius et al, Super. Sci. Tech. 2004

12 Difference in RT: conventional way vs our approach Resistance (ohm) No cleaning Conventional bolometer shows one transition temperature R n 200 Ω Poor interface Transparency 0 Resistance (ohm) Temperature (K) In situ cleaning + 10 nm NbTiN brings T c back to 7 K R n 60 Ω (expected) Improved interface Transparency ~5 % Temperature (K)

13 Noise and IF gain bandwidth data (Spiral antenna) I [µa] Device G optimum optics in-situ Ar cleaning + 10 nm NbTiN V [mv] 3000 At 2.5 THz: T N,DSB =950 K underpumped opt. pumped overpumped2500 At 1.89 THz: T N,DSB =750 K opt. pumped overpumped Tn [K] relative IF Gain [db] Opt. Bias (a) High Bias (b) 6 GHz 1 10 IF Frequency [GHz] 750 K at 1.9 and 950 K at 2.5 THz ( ~8 hν/k) 6 GHz IF gain bandwidth Best ever measured

14 Progress in twin slot antenna mixers Twin slot is needed for real application (beam pattern & polarization) Design with a central frequency of 1.8 (or 1.6) THz We realized HEB with a size from 2 µm 0.3 µm to 1 µm 0.1 µm Small HEB volume for low LO power

15 Space applications+using solid state LO reduce HEB size I [µa] Device M6T_K3 1x0.15 um 1. 6THz twin slot NbN HEBM T=4.45 K F IF =1.35 GHz lens without AR coating. unpumped Lo0 45 nw Lo1 62 nw Lo2 34 nw T n,dsb [K] Y=0.71 db=1120 K K with coated lens 1200 Direct detection is 0.1 opt bias V [mv] 1 µm (width) x 0.15 µm (Length) Receiver Noise Temperatures remains nearly the same (only 10 % increase for 1 µm x 0.1 µm small devices) LO power in HEB is reduced : 30 nw (by isothermal technique) 200 nw at the mixer lens

16 6 smallest devices from 3 different batches: Highly reproducibility Device Antenna f(center) Size (W L) µm µm I C (4 K) Freg. LO Rec. T N P LO (Iso.th) P LO (at lens) M6T-3K Twin slot (1.6 THz) µa 1.63 THz 910 K* 40 nw 0.22 µw M6T-2K Twin slot (1.6 THz) µa 1.63 THz 960 K* 30 nw 0.17 µw M6T-11K Twin slot (1.8 THz) µa 1.89 THz 1060 K* 30 nw 0.17 µw M6T-9L Twin slot (1.8 THz) µa 1.89 THz 1030 K* ~25 nw ~0.15 µw M8T-H1 Twin slot (1.8 THz) µa 1.89 THz 990 K* 70 nw 0.39 µw M9T-C3 Twin slot (1.6 THz) µa 1.63 THz 930 K* 90 nw 0.50 µw

17 NbN Superconductor Hot Electron Bolometer Mixers II: Plan Reproduce the best results using twin slot antenna HEB device physics Reduce HEB size to reduce the LO requirement Try new idea to increase IF bandwidth Going to frequencies between 3-5 THz ( QC laser) 1.8 THz twin slot design will be verified in TELIS Balloon Observatory (1.8 THz) (DLR, Germany)

18 Kinetic inductance detectors Hardware ready July 1 st 2004 He3 cooler, Ta, Nb Technician Niels Hovenier PhD student in the process of selection