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HCS 40-K on DN40 (O.D. 2.75") CF-flange with all metal leak valve

• Highly efficient thermal H₂ cracking
• Absolutely ion-free hydrogen beam
• High H-flux applications
• Very clean operation
• Compatible with all MBE systems
• On flange integrated cooling shroud
• Low power consumption

The Hydrogen Cracker Source - HCS - is a thermal gas cracker which produces an absolutely ion-free hydrogen gas beam to avoid ion induced damage of the substrate.

Atomic hydrogen is generated in a hot tungsten tube, heated by electron bombardment up to 2100°C. The tube diameter of 4 mm also allows high hydrogen flux applications.
In comparison to the GRZ the HCS provides higher gas throughput, more homogenous angular distribution of the atomic H beam and improved cracking efficiency. The closed and well shielded design of the heater, as well as the integrated cooling shroud, avoid interaction of the electron beam with other MBE chamber equipment. Due to the very efficient heating mechanism the power consumption is relatively low (e.g. 200 W for T=2000°C).
The integrated TC touches the W-tube in the upper area allowing precise temperature display and control.
Very clean operation is achieved by a design, that lets the hydrogen gas touch the stainless steel parts in cold areas only and the tungsten tube in the hot zone only. Further refractory metal parts only are in contact with the hot filament and gas line tube.

We recommend to use the HCS with a bakeable all metal leak valve and a gas purifying system to achieve highest purity operation. We provide a complete Gas Injection System for atomic hydrogen. The HCS is delivered with a special power supply which provides the filament power and the high voltage needed for the electron bombardment heater.

Main parts of the hydrogen cracker source HCS

Gas Injection System
For optimised performance we provide a complete Gas Injection System for atomic hydrogen. The Gas Injection System is completely mounted and only an H2 gas bottle is needed to start operation. A simple turbo molecular pump can be used to evacuate the H2 gas line. The H2 gas line and the all metal leak valve can be baked up to 180°C.

• fully UHV compatible
• H2 gas cracking cell
• all metal leak valve
• flexible UHV tube 1m max. length
• H2 gas purifier
• H2 stainless steel gas pressure reducing system
• all metal valve for evacuation
• bakeable system (180°C)
• power supply
• Eurotherm controller
• power cables 5m
• TC extension wire 5m
• H2 bottle - not included!!!

Application

Typical applications for the HCS are low temperature surface cleaning, promotion of 2D growth of GaAs, enhancing of GaN growth rate or H surfactant growth in Si or GaAs MBE.

Low Temperature Surface Cleaning of InP and GaAs
In MBE the cleaning of substrate surfaces is very important to reach high quality epitaxial films. GaAs or InP substrate wafers can be cleaned while being irradiated with atomic H. Carbon contamination is removed at temperatures as low as about 200°C and oxygen at temperatures of about 400°C.
[T. Sugaya, et al., Jpn. J. Appl. Phys. 30 (1991) L402]

Si Substrate Preparation / GaAs on Si
Atomic hydrogen is also used for in-situ cleaning of Si substrates, leading to significant reductions in surface contamination. Atomic hydrogen irradiation has also been used during growth of GaAs on Si substrates to achieve lower defect densities.
[H. Shimomura, et al., Jpn. J. Appl. Phys. 31 (1992) L628]
[Y. Okada, et al., Jpn. J. Appl. Phys. 32 (1993) L1556]
[H. Shimomura, et al., Jpn. J. Appl. Phys. 32 (1993) 632]

Promotion of 2D Growth of GaAs
Improved properties of MBE grown GaAs is reported after atomic hydrogen enhanced growth, compared to standard grown GaAs.
[H. Shimomura, et al., Jpn. J. Appl. Phys. 32 (1993) L632]
[Y.J. Chun, et al., Jpn. J. Appl. Phys. 32 (1993) L1085]

Selective Epitaxial Growth in MBE and GS MBE
Another feature of atomic hydrogen enhanced MBE growth is selective epitaxial growth. This technique allows a local selective deposition of MBE related materials onto a prepared substrate.
[T. Sugaya, et al., Jpn. J. Appl. Phys. 31 (1992) L731]
[N. Kuroda, et al., Jpn. J. Appl. Phys. 32 (1993) L1627]

Technical Data

Dimensions

Specific Data

 LAST UPDATE: NOVEMBER, 2004

© 2003 Dr. Eberl MBE-Komponenten GmbH