Joe Beach
CSM Physics Department, Meyer Hall, Room 447
1523 Illinois Street, Golden CO 80401-1887
Phone: 303-384-2176
Fax: 303-273-3919
E-mail: jbeach@mines.edu

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Useful Laboratory Items

The following are some files and bits of information that have turned out to be useful for me when I have been working in the lab. Waste log sheets, printer drivers, etching recipies, and such. Some things are specific to labs at CSM, while others are more generally useful.

Waste container log sheet

Unlabeled bottles of mixed waste are potentially dangerous and their disposal is expensive. It is a good practie to keep track of what goes into mixed waste bottles (an acid waste bottle, for example) so you know exactly what is in them. This is especially the case when someday you will have to be the responsible party submitting them for disposal. Here is a waste bottle label for that purpose.

GaAs oxide stripper

This is a good process for removing the oxide layer on GaAs prior to ohmic contact deposition. Mix a solution of 10:2:1 water:ammonium hydroxide:hydrogen peroxide. The hydrogen peroxide should be the concentrated, 30% variety. Make the solution fresh before use, and use it at room temperature. It takes 1-2 minutes to remove the oxide, and does not etch the bare GaAs surface. With heavily oxidized material, you can actually see the film lift off.

Drierite regeneration

According to the Drierite website, http://www.drierite.com, Drierite can be regenerated by baking it. The "Regular" and "Indicating" Drierite should be spread one grain deep in a tray and baked at 210 C for 1 hour. The "Commercial" or "Du-cal" Drierite should be spread 1 inch deep in a tray and baked at 210 C for two hours. The baking temperature can be reduced if a vacuum oven is used. For a 26" Hg vacuum, bake at 325 F. For a 28" Hg, bake at 275 F. Baking at higher temperatures can change the crystal structure of the Drierite, removing its hygroscopic properties. The active ingredient in Drierite is CaSO4. The "Indicating" Drierite also contains CoCl2, which turns pink as it hydrates. Repeated regenerations will eventually disable the indicator.

HP Deskjet 722c printer drivers for Microsoft Windows 3.1x

The KLA-Tencor P-10 profilometer, which we have in the CSM Center for Solar and Electronic Materials, uses MS Windows 3.1. It turns out that it is getting difficult to find deskjet printers that come with drivers for that operating system. Here is a zipped file of the driver installation diskettes for the HP 722c under MS W3.1. To install the drivers, do the following: unzip the file; copy the contents of the directories "DISK1", "DISK2", "DISK3", and "DISK4" to separate 1.44 Mb diskettes; insert Disk 1 into the profilometer computer; switch to the diskette drive and run "setup.exe"; follow the rest of the on-screen instructions.

Data aquisition with a Vaisala HM70 humidity meter

Due to a lack of manufacturer support, I had to do a bit of extra work to acquire data from a Vaisala HM70 humidity meter in the way that I wanted. This link describes the commands and data formats that I needed to figure out to make it work.