The AXUV63HS1 and AXUV63HS1-CH are the large-area members of Opto Diode’s high-speed circular AXUV photodiode line, built by Opto Diode, a division of ITW, in Camarillo, California. Both put a Φ9 mm (63 mm²) circular active area behind a windowless silicon entrance, and both are specified for electron detection at nanosecond-class speed. The difference is geometry: the AXUV63HS1-CH carries a Φ1.00 mm hole through the center of the detector, listed on its datasheet as “Hole in Center of Detector.”
Where these two sit in the high-speed circular AXUV line
Opto Diode’s current catalog lists three high-speed circular AXUV photodiodes. The AXUV20HS1 is the small-area, fastest member; the two 63 mm² parts on this page trade rise time for roughly three times the collection area. All three quote rise time at the same test condition, so the comparison below is like for like.
| Model | Part number | Active area | Rise time, max (RL = 50 Ω, VR = 150 V) |
Geometry |
|---|---|---|---|---|
| AXUV20HS1 | ODD-AXU-036 | Φ5.01 mm — 20 mm² | 3.5 ns | Solid circular |
| AXUV63HS1 | ODD-AXU-049 | Φ9 mm — 63 mm² | 10 ns | Solid circular |
| AXUV63HS1-CH | ODD-AXU-051 | Φ9 mm — 63 mm² | 9 ns | Circular, hole in center |
Like all AXUV detectors, these are windowless silicon devices: the family measures photons, electrons or x-rays from 0.0124 nm to 190 nm and detects energy from 100 eV to 50 keV with 100% internal quantum efficiency, because the silicon has no surface dead region and the entrance window is a passivating oxide only a few nanometers thick.
AXUV63HS1 electro-optical characteristics at 25 °C
| Parameter | Test conditions | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Active area | Φ9 mm | — | 63 | — | mm² |
| Responsivity | see graphs in datasheet | specified as a curve | A/W | ||
| Reverse breakdown voltage, VR | IR = 1 µA | 160 | — | — | V |
| Capacitance, C | VR = 0 V | — | 700 | 2000 | pF |
| Rise time | RL = 50 Ω, VR = 150 V | — | — | 10 | ns |
| Dark current | VR = 150 V | — | — | 100 | nA |
Datasheet FEATURES for the AXUV63HS1: circular active area, ideal for electron detection, high speed, and a protective cover plate. The capacitance-versus-voltage curve in the datasheet runs from 0 V to 150 V; the table specifies a numeric value only at zero bias, so read the curve for anything in between.
AXUV63HS1-CH electro-optical characteristics at 25 °C
| Parameter | Test conditions | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Active area | Φ9 mm | — | 63 | — | mm² |
| Responsivity | see graphs in datasheet | specified as a curve | A/W | ||
| Reverse breakdown voltage, VR | IR = 1 µA | 160 | — | — | V |
| Capacitance, C | VR = 0 V | — | 1 | 10 | nF |
| Capacitance, C | VR = 150 V | — | 85 | — | pF |
| Rise time | VR = 150 V, RL = 50 Ω | — | — | 9 | ns |
| Dark current | VR = 150 V | — | — | 100 | nA |
Why the AXUV63HS1-CH lists capacitance twice Junction capacitance falls as reverse bias widens the depletion region, so a single number means nothing without its bias condition. The AXUV63HS1-CH datasheet specifies both ends of that range: 1 nF typical and 10 nF maximum at zero bias, and 85 pF typical at the 150 V operating bias used for the rise-time and dark-current specifications. Design the front end around the biased figure if you intend to run the detector at 150 V, and around the zero-bias figure if you do not. Note that the two parts are specified differently here — the solid AXUV63HS1 quotes capacitance only at VR = 0 V — so their zero-bias numbers are not directly comparable with the -CH’s biased number.
The 160 V breakdown figure is a limit, not a setting
Both datasheets specify reverse breakdown voltage as a minimum of 160 V, defined at a reverse current of 1 µA. That is a guaranteed floor on where the device breaks down, not an operating recommendation: a given unit may break down at 160 V or well above it. The specified operating bias for rise time and dark current on both parts is 150 V, exactly 10 V below that floor. Neither datasheet publishes an absolute-maximum reverse-voltage rating, so the safe design rule is to treat 160 V as the ceiling and size the bias supply so that it cannot overshoot into it — including at turn-on and under fault conditions.
What the center hole is for
The AXUV63HS1-CH datasheet lists “Hole in Center of Detector” among its FEATURES. Opto Diode’s AXUV operating-principles note records the heritage of that geometry: quadrant AXUV diodes with central holes and rectangular slit openings “were built specifically for synchrotron beam intensity monitoring and position sensing.” The current catalog carries a center-hole part — this one — and a quad part, the AXUVPS7.
Note the limit of that heritage: the passage above describes quadrant diodes, and the AXUV63HS1-CH is a single circular element, so it cannot itself resolve position. Opto Diode does not document an intended use for this part’s aperture beyond the FEATURES line; geometrically, an on-axis hole lets a beam pass through the detector plane while the surrounding silicon measures what falls around it. The package drawing on page 3 of the AXUV63HS1-CH datasheet dimensions the aperture: a Φ1.00 mm (Φ0.039″) hole through the center of the Φ9.00 mm active area, opening to a Φ2.50 mm (Φ0.098″) backside hole. The hole is not deducted from the specified area — the electro-optical table lists the same Φ9 mm, 63 mm² typical active area for both parts. Check the package drawing against your beam geometry, and talk to our applications engineers before committing to a mounting design.
Temperature ratings and handling
Both parts carry identical thermal specifications.
| Storage & operating range | Rating |
|---|---|
| Ambient | −10 °C to 40 °C |
| Nitrogen or vacuum | −20 °C to 80 °C |
| Lead soldering temperature | 260 °C (0.080″ from case, 10 seconds) |
Temperatures exceeding the ambient rating can create oxide growth on the active area; over time, responsivity to low-energy radiation and to wavelengths below 150 nm will be compromised. The wider nitrogen-or-vacuum range is the one that matters for beamline and chamber installations.
Handling note Both parts ship with a temporary cover protecting the photodiode and its wire bonds. Review the application note Handling Precautions for AXUV, SXUV, and UVG Detectors before removing the cover.
Where these detectors are used
Opto Diode lists three applications for the AXUV family: electron detection, synchrotron radiation monitoring, and electron reticle inspection. Both 63 mm² parts are specified as ideal for electron detection, and their nanosecond-class rise times suit fast or pulsed measurements within those applications. The large active area is the reason to choose them over the AXUV20HS1: three times the collection area for weak or diffuse signals, at the cost of roughly three times the rise time and substantially higher capacitance. Where the measurement is a beam that must continue past the detector, the AXUV63HS1-CH is the geometry to evaluate.
Related AXUV detectors
Request a quote or check availability
The AXUV63HS1 (Opto Diode part number ODD-AXU-049) and the AXUV63HS1-CH (ODD-AXU-051) are available direct from Opto Diode; the AXUV63HS1 is also listed by Digi-Key. Standard response to an online request is within 1–2 business days; direct orders must meet a $3,000 minimum.
Frequently Asked Questions
What is the difference between the AXUV63HS1 and the AXUV63HS1-CH?
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Geometry. Both specify the same Φ9 mm, 63 mm² typical circular active area, the same 160 V minimum reverse breakdown voltage at IR = 1 µA, and the same 100 nA maximum dark current at VR = 150 V. The AXUV63HS1-CH adds a hole through the center of the detector, and it is specified slightly faster at 9 ns maximum rise time against 10 ns for the solid AXUV63HS1, both measured with a 50 Ω load at 150 V reverse bias. The hole is dimensioned in the package drawing rather than the specification table: Φ1.00 mm through the center of the Φ9.00 mm active area, opening to a Φ2.50 mm backside hole.
How fast are the AXUV63HS1 and AXUV63HS1-CH?
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Maximum rise time is 10 nanoseconds for the AXUV63HS1 and 9 nanoseconds for the AXUV63HS1-CH, both measured with a 50 Ω load at 150 V reverse bias. For comparison, the smaller-area AXUV20HS1 is specified at 3.5 nanoseconds under the same conditions.
Why does the AXUV63HS1-CH datasheet list capacitance twice?
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Because junction capacitance falls as reverse bias widens the depletion region, so the figure is meaningless without its bias condition. The datasheet specifies 1 nF typical and 10 nF maximum at VR = 0 V, and 85 pF typical at VR = 150 V, the same bias used for the rise-time and dark-current specifications. Use the biased figure if you intend to operate the detector at 150 V.
How do I buy the AXUV63HS1 or AXUV63HS1-CH?
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Contact Opto Diode directly for a quote — the standard response time for an online request is within 1–2 business days. Direct orders are subject to a $3,000 order minimum. Opto Diode’s part numbers are ODD-AXU-049 for the AXUV63HS1 and ODD-AXU-051 for the AXUV63HS1-CH; the AXUV63HS1 is also listed by Digi-Key.
Specifications from the AXUV63HS1 and AXUV63HS1-CH datasheets, both Revision October 10, 2024. Reviewed and updated August 2026.