Low Temperature

Low Temperature

Selenium Valved Cracker

Selenium Valved Cracker

Used By Leading II-VI Research Groups Worldwide

This source has multiple heating zones that can either generate cracked or uncracked selenium flux while resisting the chemical attack from the corrosive vapor. The unrivaled convenience and flux control are maintained without depleting the source material via an all-metal needle valve. Excellent results have been reported producing blue/green LED and laser diode devices.

  • Patented design with more than 50 in the field
  • Provides flux modulation and on/off control
  • Large source capacity
  • Utilizes a nozzle for excellent flux uniformity and reduced material waste
  • Prevents loss of source material during system bakeout
  • Utilized by leading II-VI research groups worldwide with more than 50 in the field

The Veeco Valved Cracker for Selenium is used by leading II-VI research groups worldwide. Its multiple heating zones can be operated to generate a cracked or uncracked selenium flux. An all-metal needle valve regulates the gas flow from the crucible through the conductance tube to the growth module. The conductance tube is constructed of tantalum for resistance to chemical attack from selenium vapor.

With recent enhancements, the Mark V Valved Cracker for Selenium incorporates a nozzle that provides excellent flux uniformity and reduced material waste. This improvement in material utilization results in:

  • Material cost savings
  • Longer campaigns
  • Less hazardous waste generation
  • Reduced memory effects
  • Lower particulate levels and flakin
  • Reduced system window coating

The Veeco Valved Cracker for Selenium is available in 500cc and 1200cc sizes for compatibility with various MBE systems. The exit nozzle is customized to the specific MBE system for excellent flux uniformity across the wafer or platen. A Veeco SMC-II Automated Valve Positioner is recommended for use with this source for reliable, automated control of the needle valve.

Performance and Benefits

The Veeco Valved Source for Selenium offers convenience and flux control unrivaled by any standard source. Control over the growth process is optimized using a needle valve for nearly instantaneous flux modulations and complete flux shut-off. The source may be idled continuously at operating temperature without depleting the charge material. With mechanical flux control, rather than the thermal control used for conventional open sources, the charge capacity may be arbitrarily large without limiting the responsiveness of the source.

Benefits include:

  • Longer growth campaigns
  • Charge preservation during bakeout and idle periods
  • More thorough charge outgassing
  • Lower unintentional Group VI background in the system

Excellent flux stability and responsiveness have been demonstrated with the successful growth of blue/green light-emitting diodes and laser diodes based on ZnMgSSe/ZnSSe/ZnCdSe.

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