This year, Vigo launches RoHS compliant MWIR and LWIR photodetectors operating at ambient temperature or at temperatures achievable with thermoelectric coolers (TEC). The devices have a performance similar to their HgCdTe-based counterparts and show significantly better resistance to environmental exposure.

Despite many advantages devices containing heavy metals (Hg, Cd and Pb are successively removed from the consumer market through norms and directives (e.g. RoHS) due to their toxicity.

The A3B5 semiconductors are a great candidate to replace HgCdTe and PbSe in fabrication of photodetectors. After years of intensive research and development work, VIGO is ready to present the first generation of photoconductors and photovoltaic MWIR and LWIR devices based on the complex heterostructures with InAs/InAsSb superlattice absorbers.

The devices are characterized by performance comparable with their MCT and PbTe counterparts operating at the same spectral and temperature ranges. The devices also have a significantly better resistance to environmental exposure.

 

MWIR Superlattice-based photodiodes

For MWIR detection VIGO is developing SL detectors operating at room temperature or with thermoelectric coolers. Recent results show that SL-based detectors exhibit higher resistance area (RA) product in comparison to bulk InAsSb devices.

Features:

  • Cut-on wavelength limited by transmission of GaSb buffer ~1.7 μm
  • High RA product and D* similar to MCT (Fig. 2)
  • RoHS compliant product
  • Wider spectral range.
  • Flicker-noise free operation without bias
  • Very fast response with reverse bias,better frequency response than PbSe detectors
Parameter Detector type
Photovoltaic
Absorber material Type of photodiode

InAs/InAsSb

backside illuminated
Active element temperature, K 300 230
TEC Non-cooled 2-stage
Peak wavelength, µm 4.0 – 4.5
Spectral range, µm 1.7 – 6.0 1.7 – 5.7
λCutoff (10%), µm ~6.0 ~5.7
D* (λpeak), cm·Hz1/2/W >5 x 108 >4 x 109
Responsivity (λpeak), A/W >0.7 >1.4
Shunt impedance (@VR =10 mV), Ω >110 >1000
Active area dimensions, mm 0.1 x 0.1 1 x 1 immersed
Package TO-39 TO-8
* 1 x 1 mm on request

ROADMAP of MWIR InAs/InAsSb SL Detectors

Q1-Q2 2021

Samples available for testing:

Active area:

• 0.1×0.1 mm

• 1×1 mm immersed

• 1×1  flat cooled device(on special request)

 

Q3-Q4 2021

Further development:

• improved architectures to reach higher RA product and increased detectivity

• suppressed fringing

• optimized spectral response

• cascade MWIR devices with significantly increased resistance

LWIR Superlattice Detectors

LWIR Superlattice Detectors

VIGO is developing a variety of LWIR uncooled or Peltier cooled PC and PV devices with cutoff wavelength up to ~15 µm. Recent results show that the SL detectors exhibit the performance close or sometimes, better compared to that o HgCdTe devices. This is the first RoHS compliant product for LWIR detection that does not require liquid nitrogen cooling! An example is the LWIR photoconductor with the spectral response shown in Fig. 3

Features:

  • Cut-on wavelength limited by tansmission of buffer layer ~1,7 um
  • Higher D* compared to bulk PC InAsSb and thermopile detectors
  • RoHS compliant product
  • Very good stability ideal for harsh environment
  • 50% cut-off wavelength optimized for 10 or 12 μm
  • Convenient operation with Peltier cooling.
Parameter
Detector type
Immersed 3TE photoconductive
Absorber material
Type of photodiode

InAs/InAsSb

backside illuminated

Active element temperature, K210
Peak wavelength, µm7.0 – 9.0
Spectral range, µm1.7 – ~12
λCutoff (10%), µm~12
D*(λpeak), cm·Hz1/2/W (@0.5 V)>3 x 109
Resistance , Ω>60
Active optical area , mm1 x 1
Package (window)

TO-8 (wZnSeAR)

* 1 x 1 mm on request

ROADMAP of LWIR InAs/InAsSb SL Detectors

Q1-Q2 2021

Samples available for testing:

Active area:

1×1 immersed

1×1 or 0.1×0.1 *(on special request)

Q3-Q4 2021

Further development:

• improved architecture and PV devices

• antifringing and antireflective layers

• optimized spectral response

• flicker noise free cascade devices operating
at zero bias

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If you are interested to base your new project on the above products we offer full technical support included products samples and help in implementation of our detectors. 

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