Provides sulfur flux rates for R&D applications on a DN40CF flange
Flux regulation and on/off control by motorized valve
UHV-tight valve
Water-cooled cracker with beam shaping nozzle
12 cm³ or 150 cm³ reservoir
Reservoir and valve are located ex vacuum
The Valved Sulfur Source VSS aims at R&D applications where valve controlled small or medium flux rates of high vapor pressure materials are required. The reservoir and the valve are both located ex vacuum. This offers a huge benefit for reloading the reservoir or maintenance work, which can be done without venting the chamber. The reservoir and valve are heated by industrial grade electrical heaters and are both temperature controlled with high accurate Pt100 thermometers. In order to achieve the highest possible cleanliness all critical welds for the valve and reservoir are prepared by electron beam welding. |
![]() Schematic of VSS 1 case, 2 vacuum chamber 3 stepper motor for valve regulation 4 material reservoir, 5 valve 6 PBN injector tube, 7 cracker insert, 8 shutter 9 electrical heater, 10 water cooling |
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The VSS is designed for reservoir temperatures up to 250°C and works smoothly down to 100°C. The internal thermal design ensures ideal temperature gradients for trouble free operation. To ensure maximum process control this cell offers four independent heating circuits (reservoir, valve, pipe, cracker). However, depending on application the cell can be operated by using three circuits only. The VSS is equipped with a high precision stepper motor that controls the valve. Hence, flux modulations in the order of two magnitudes are typically obtainable. For other applications pneumatic and manual valve control is also available. There are two different valve types available for the VSS, namely a high throughput variation with higher overall throughput and one valve with smaller throughput but finer flux regulation characteristics. See the figure on the right for information about valve characteristic. |
![]() Valve characteristic for |
ApplicationA source concept like this is used for high vapor pressure materials, which form atom clusters. Typical evaporation elements are S and Se. The in-vacuum length of the VSS is either 220 mm or 287 mm. Other in vacuum lengths are achievable using application specific spacers. By default the cracker insert will be made from pyrolytic boron nitride, which will ensure efficient cracking for sulfur and selenium. |
![]() Temperature / time chart for an operation example of the VSS 40-150-51. The shown temperature curves can be separated in three procedure steps: heat up (0-140 min), growth window (140-145 min) and cool down (145 min – 220 min) |
Technical data |
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General | |
Port to chamber | DN40CF (2.75” O.D.) |
In vacuum diameter | 36 mm |
Bakeout temperature | 200°C |
Shutter opening angle | 90° ccw |
Cooling water flow | 30-60 l/h |
Weight | 13 kg (VSS 40-150-51-KS-RV-P-MC-L220D36) |
Surface temperature | typical 60°C, maximum 90°C (touch protection available) |
Reservoir | |
Heater type | industrial grade electrical heater 80 W / 42 V |
Temperature sensor | Pt100 Class A 3-wire configuration |
Operating temperature | 100 - 250 °C |
Maximum temperature | 300°C |
Cooling | none |
Capacity options | 150 cm³ 12 cm³ |
Valve | |
Heater type | industrial grade electrical heater 80 W / 42 V |
Temperature sensor | Pt100 Class A 3-wire configuration |
Operating temperature | 100-250 °C |
Maximum temperature | 270°C |
Cooling | none |
Types | high throughput version (Option: -TV) fine regulation version (Option: -RV) |
Control options | motorized (Option: -MC) pneumatic (Option: -PC) manual (Option: -HC) |
Injector pipe | |
Length of tube | 220 mm or 287 mm |
Heater type | tantalum wire filament |
Cooling | none |
Operating temperature | 200-400°C |
Temperature sensor | W5%Re/W26%Re (type C) |
Options | integrated rotary shutter (-S) |
Cracker | |
Operating temperature | 300 - 1200°C |
Maximum temperature | 1400°C |
Heater type | tantalum wire filament |
Temperature sensor | W5%Re/W26%Re (type C) |
Cooling | integrated water cooling shroud |
Cracking insert | PBN or graphite |
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Schematic drawing of a Valved Sulfur Source VSS |
For general information on CF mounting flanges see Flange and Gasket dimensions.
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[cm3] | [mm] | [mm] / [mm] | Product code | |||||||
VSS | 40 - | 150 - | 51 - | K | S - | RV - | MC - | LxxxD36 | 1 x PS 30-10¹ 2 x PS 75-2 |
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VSS | 40 - | 150 - | 51 - | K | S - | RV - | HC - | LxxxD36 | 1 x PS 30-10¹ 2 x PS 75-2 |
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VSS | 40 - | 150 - | 51 - | K | S - | TV - | PC - | LxxxD36 | 1 x PS 30-10¹ 2 x PS 75-2 |
* | rotary shutter possible on same flange (option S) | 1 | Power supplies for cracker heater; for optional pipe heater an additional PS 30-10 power supply is needed | |
*** | specify UHV length L with order (L = 220 mm or L = 287 mm) |
- Motorized Valve Control Unit MVCU
- Rotary Shutter Module RSM
Product code:
e.g. VSS 40-150-51-KS-RV-MC-L220D36
is a valved sulfur cracker source on DN40CF flange with 150 cm³ nominal reservoir capacity, integrated cooling shroud and shutter, fine regulation valve and motorized valve control, in-vacuum length 220 mm and outer diameter 36 mm.