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MBE Systems

There are 3 main systems currently in use in the SP Group. Two are used for the growth of GaAs/AlGaAs/InGaAs devices on GaAs or InP substrates and one is used for the growth of GaN/AlGaN/InGaN on Sapphire or GaN templates. 

 

W Chamber

The Veeco Gen III chamber was installed in 2007 to replace two 1986 vintage VG V80H systems and is configured for the growth of high quality GaAs/AlGaAs heterostructures, InAs self assembled quantum dot devices, optical microcavities and InGaAs/InAlAs quantum well structures. Attached to the vacuum system is a separate chamber for Hydrogen cleaning of wafers before loading into the growth chamber. Equipped with 2x Gallium, 2x Aluminium, 3x Indium, Carbon, Silicon and 2x Arsenic Valved Cracker sources. Substrate temperature monitoring is by Pyrometer and kSA BandiT band edge thermometry. Optical monitoring of growth is performed using pyrometric interferometry or spectral reflectometry using the ellipsometer ports.

In its as-delivered configuration we achieved a world record mobility of 14 million cm2/Vs at 4E11/cm2 carrier density for a 300nm deep Quantum Well structure on a 3" GaAs substrate. This was the first time that this particular MBE system design has ever reached Ultra high mobilities and was achieved using large, standard sources. Work is currently underway to upgrade the system in order to increase mobility further as this parameter is a key requirement for the development of the devices used in this programme grant to study new physics. This will include the addition of a large cryopump from Oerlikon-Leybold which should improve the quality of the vacuum achieved, a novel Silicon doping source where a strip of silicon is directly heated and evaporated and modification and improvements to the in-situ growth monitoring capabilities on the chamber. Once this upgrade work is complete the focus will turn to device growth with the aim of beating the previous record for mobility on this chamber and aiming to exceed 20 million cm2/Vs - at this mobility electrons have a mean free path of 175um.

 W Chamber

V Chamber

3" Veeco Mod Gen II system installed in 2001. This system is used primarily for the THz programmes within the group and via European collaborative grants. The main focus is GaAs/AlGaAs based Quantum Cascade Laser structures. The system has Ga, Al, In, As, Si, Be and Carbon sources and is also used for the growth of high mobility structures on GaAs and InP substrates.

Veeco Mod Gen II System

A Chamber

2" Vacuum Generators VG V80H system installed in 1985. Originally used for GaAs/AlGaAs work but was refurbished in preparation for GaN growth in 2010.

 A Chamber Pre Nitride Conversion

 

 

 

 

 

 

 

 

 

 

 

 

 

VG systems use the "cassetrac" system for moving wafers around inside the vacuum chambers.

B Chamber Internals