The pics are mostly too big to try and insert into the post, so you'll have to click the links. They are on a little server I pay almost nothing for a month, but its bandwidth should be fine for here.
Just a very quick description of CVD diamond growth so the components make sense:
1) You need a chamber in which the sample is placed, and it must be pumped to a weak vacuum (about 10mT for us) to remove air and contaminants.
2) You then add hydrogen and methane as your primary gases. Other gases can be added to change the properties of the diamond. Examples include nitrogen, boron, argon and others. Some people use acetone instead of methane.
3) This gas is pumped out at a constant rate, so there is always new gas entering and new gas leaving.
4) Now you need an energy source. The energy source has two functions; first, it needs to decompose the methane so you have free carbon floating around. Secondly, your sample must be heated to a high temperature. Diamond (sp3) bonds only form above a certain temperature; below that, you get graphite. Of course, you can't have
too high a temperature or you'll melt your sample.
The original energy source (80's) were very hot filaments. Microwave plasma came along about a decade later, but has taken some time to master. There are advantages and disadvantages to both. Ours is a microwave system; you can see the 30kW microwave in the background.
http://www.pitofbabel.org/Vista/GlobalPic.jpg
There it is; it was originally operating in the Northeast, Boston area. We had to almost completely rebuild most of the system (we picked it up ourselves, and it came in many pieces). Of course, while stored up there it was subjected to freezing and warming over several cycles. There was extensive damage to the cooling system and I got to be a plumber for about a month
The big silver door held down by bolts is where the sample is inserted into the system. The sample is then raised into the microwave cavity - the black metal section - where the action happens. You can see the small window there where the sample can be viewed when you have a plasma.
http://www.pitofbabel.org/Vista/Plasma007a.jpg
For this pic I had turned off the lights. You can see the plasma glowing through the window. It's a small window, so its tough to get good pics of the sample through it.
First, a picture of our sample holder with samples, below:
http://www.pitofbabel.org/Vista/BNHolder.jpg
And some pictures with samples added. These are typical square (SPG-422) tungsten carbide 6% cobalt inserts.
http://www.pitofbabel.org/Vista/30Torr-1.jpg
http://www.pitofbabel.org/Vista/40samplePlasma.jpg
Those are old pics, but frankly they look better than my new ones. The plasma is purple because it is a hydrogen plasma; when methane and nitrogen are added it becomes white. There is a secondary plasma that forms on surfaces and corners and you can see it if you look closely in that second picture.
The actual chemistry that occurs at the surface is extremely complicated (no surprise in a plasma), and there is still ongoing research to discover what actually happens there.
Your substrate is important for good diamond growth. Diamond grows well on most of your M-C carbides (Titanium, Tungsten, Si etc) because of similar lattice structures. Of course, diamond grows best on diamond. Those pictures were taken at about 30torr. Increasing the pressure to 100 or more torr would reduce the size of the plasma but increase the growth rate considerably. That is how single crystal diamond is usually grown on diamond or saphire substrates.
Anyhow, I could certainly go into more, but I'll answer questions if there are any instead of writing a novel.
). However, unless you are in one of several technical fields, you will likely never know it.