Valve and flux control panel of the ISES 

• AsBr3 atomic precise etching
• No carrier gas required
• Full UHV and MBE compatibility
• No significant affectation on MBE growth properties
• Free standing system
• Integrated safety management
• Computer controlled operation
• Second material optional

The In-situ Etching System - ISES - is a fully UHV and MBE compatible gas source for high vapour pressure materials like AsBr3 which is used for in-situ etching applications.
AsBr3 in-situ etching provides atomic layer precise manipulation of thin films and nanostructures. The use of AsBr3 as the etchant species without any carrier gas guaranties full compatibility to all standard III-V-MBE systems. Due to the very small amount of AsBr3 which is injected into the MBE system, no extra installations (extra pumps etc) are needed and no significant interaction, corrosion, etc of the MBE system is observed even after several years of operation.

AsBr₃ etching mechanism

The in-situ etching system is a stand-alone system which requires external supply of compressed air, clean N2, cooling water and waste air as well as electrical power. Only a free DN40 CF (O.D. 2.75") flange for the gas injector unit is needed to connect to the MBE system.

The solid state (or liquid) etchant material is stored and evaporated in a gas cabinet. The gas cabinet also includes a mass flow controller (MFC) for vapour flow control and an own UHV system to provide a continuous flow and for evacuating the gas system to achieve high purity operation conditions. An exhaust filter and an integrated gas alert system guarantees a safe and non-polluting operation.
All equipment needed for operation is mounted into the gas cabinet and therefore it represents a compact and easy handing tool. Most electronic controllers have integrated standard computer interfaces which enables fully automated operation.
Optionally the in-situ etching system can be extended to a second material source as well as to a second gas injector unit.

Gas cabinet of the AsBr₃ in-situ etching system ISES

Application

AsBr3 in-situ etching allows atomic precise layer by layer etching inverse to the layer by layer MBE growth. The figure above shows RHEED oscillations of a typical growth - etching sequence indicating the precise removal of 6 monolayers of GaAs which have been deposited earlier. Due to the lower etching rate of AlAs the oscillations slow down after the removal of the GaAs and when the AlAs layers are reached.

Material selectivity is a typical property of AsBr3 etching of the group III-metal atoms. Indium shows the highest etching rate while Aluminium shows the lowest rate of the group III atoms In, Ga and Al. An application is for example the growth of etch-stop layers for precise etching depth control or the modification of self assembled InAs or InGaAs quantum dots.

Forming of smooth surface facets by in-situ etching

V-grove formed by in-situ etching of a patterned GaAs sample

Forming of stripe structures by in-situ etching of masked GaAs sample

References

• Hierarchical self-assembly of GaAs / AlGaAs quantum dots
  A. Rastelli, S. Stufler, A. Schliwa, R. Songmuang, C. Manzano, G. Costantini, K. Kern, A. Zrenner, D. Bimberg and O.G. Schmidt, Physical Review Letters, accepted
• Self-assembled nanoholes and lateral QD bi-molecules by molecular beam epitaxy and atomically precise in situ etching
  S.Kiravittaya, R.Songmuang, N.Y.Jin-Phillipp, S.Panyakeow, O.G.Schmidt, J Cryst Growth 251 (2003) 258-263
• Formation of lateral quantum dot molecules around self-assembled nanoholes
  R. Songmuang, S. Kiravittaya and O.G. Schmidt, Applied Physics Letters 82, 2892 (2003)
• In-situ etching and regrowth in III-V molecular beam epitaxy for future nanotechnology
  H. Schuler, M. Keller, M. Lipinski, K. Eberl, Journal of Vacuum Science and Technology B 18: (3) 1557-1561 (May-Jun 2000)
• Systematic growth studies of narrow constrictions formed by molecular beam epitaxy on…
  Lipinski M, Schuler H, Veit P, Eberl K. MAT SCI ENG B-SOLID 74: (1-3) 25-31 MAY 1 2000
• In-situ etching with AsBr3 and regrowth in molecular beam epitaxy
  H. Schuler, T. Kaneko, M. Lipinski and K. Eberl, Semiconductor Science and Technology 15, 169 (2000)
• In-situ etching an regrowth in III/V MBE for future nanotechnology
  H. Schuler, M. Keller, M. Lipinski, K. Eberl, J. Weis and K. v. Klitzing, J. Vac. Sci. Technol 15: (2) 169-177 FEB 2000
• Size and shape modification of self assembled InAs quantum dots and stacked layers by in-situ etching
  H. Schuler and K. Eberl, Microelectronics Journal 30, 341 (1999)
• Atomic Layer In-situ Etching and MBE-Regrowth
  K. Eberl, M. Lipinski and H. Schuler, Journal of Crystal Growth 202: 568-573 (May 1999)
• Size modification of self-assembled InAs quantum dots by in-situ etching
  H. Schuler, N.Y. Jin-Phillipp, F. Phillipp, and K. Eberl, Semiconductor Science and Technol. 13, 1341 (1998)
• The effect of surface reconstruction on the surface morphology during in-situ etching
  Ritz M, Kaneko T. Eberl K. Appl. Phys. Lett. 71, 695, 1997

Technical Data

 LAST UPDATE: NOVEMBER, 2004

© 2003 Dr. Eberl MBE-Komponenten GmbH