New Material ErAs:GaAs

Mary Tang mtang at
Wed Apr 27 19:05:28 PDT 2011

Hi all --

On the face of it, this should be OK because there's no high temp 
processing or etching.  However, I've got a few questions:

1.  GaAs ought to be OK, but I'm not familiar with ErAs.  Will the 
temperatures for vacuum prime and LOL bake be compatible with this 
film?  I'm assuming the film is chemically compatible with developer 
(<2% TMAH)?  And acetone (is there a lift-off we're missing)?  I think 
that as long as this film is stable under these conditions and not 
incompatible with the chemicals it will come into contact with, it 
should be OK.

2.  Pieces are teeny -- smaller, I think, than the smallest chuck.  He 
should make sure to check with the litho folks about proper procedures 
for handling small pieces on the headway (maybe even the karlsuss too.)

3.  Baking of LOL does not need to be in the BlueM oven and is most 
often done on a hot plate.

Mahnaz might have some inputs about the litho.  But I would suggest a 
quick confirmation from the collaborator about the chemical 
compatibility with the chemicals to be used would satisfy my paranoia.  
I don't think the small quantity would pose any problem, but if we open 
the door to ErAs, it would be good to have additional info.  A google 
search turn up American Elements which supplies bulk ErAs and mentions 
an MSDS -- think we should ask him to get this?


On 4/27/2011 2:45 PM, Mike Kozina wrote:
> Hello,
> I would like to bring a new material, ErAs:GaAs, into the SNF and am seeking your approval.
> Personal Information:
> Name: Michael Kozina
> Coral login: mkozina
> Phone Number: 650-926-5382 (work), 209-662-1094 (cell)
> Email: mkozina at
> PI: David Reis, Department of Applied Physics/PULSE (SLAC)
> Chemical:
> This is GaAs with a thin (1.8micron) layer on top of ErAs islands interspersed in GaAs. I do not have an MSDS for this material (it is a new material developed by a collaborator). I am not sure of the specific Storage Group Identifier that would be most appropriate, but it seems that what works for GaAs should also work for this. Moreover, the same hazards that apply to GaAs apply to this material.
> The material was made by Art Gossard's group in the Materials Science Department at UC Santa Barbara.
> Website:
> Phone: 805 893-2686
> Reason for Request: We are studying various properties of this specific material, and we want to be able to put a certain pattern of gold on it. We don't have the facilities ourselves, and want to use the nanofab lab. There is no new procedure involved here per se--we're just going to use photolithography and sputtering to partially cover 4x4mm pieces of ErAs:GaAs.
> Process Flow (note I don't plan on using equipment that are solely "clean"--ie everything will be at the gold-contaminated level):
> 1. Prime with HMDS in YES oven.
> 2. Spin on LOL with the headway.
> 3. Bake on LOL in Blue-M oven.
> 4. Spin on photoresist with headway.
> 5. Bake on photoresist.
> 6. Expose using Karl Suss
> 7. Develop at wbmiscres.
> 8. Metallize with metallica.
> Amount and Form:
> I will bring in at most 1/4 of a 2" wafer of material. It is in solid form, divided into 4x4mm pieces.
> Storage:
> I don't plan to store this material at the SNF.
> Disposal:
> I will dispose of any sort of waste as I would for GaAs (using the appropriate As waste bins).
> Attached are three publications that detail how this material is made.
> Thanks,
> Mike Kozina

Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
Paul G. Allen Room 136, Mail Code 4070
Stanford, CA  94305
mtang at

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