Another “Periodic” Table!. Growth Techniques Ch. 1, Sect. 2, YC. Czochralski Method (LEC) (Bulk Crystals) Dash Technique Bridgeman Method Chemical Vapor Deposition (CVD) (Thin films; epitaxial film growth) Metal-Organic Chemical Vapor Deposition (MOCVD)
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a temperature gradient
along the crucible
~ 2 - 3 mm/minute
O, C are
Chemical Vapor Deposition (CVD)
Homoepitaxy:When the thin crystal layer lattice is the same as that of the substrate (e.g. Si film on Si substrate).
Heteroepitaxy:When the thin crystal layer lattice is different from that of the substrate (e.g.. GaAs film on Si).
Oh, its your standard “boy meets girl, boy loses girl, boy
invents a new deposition technique for ultra-thin film
semiconductors, boy gets girl back” story.
(The temperature of the substrate plays an important role).
SiH4 (heat) Si + 2 H2
(Silane gas) (on the substrate) (H2 gas)
NOTE!! Silane gas is highly toxic & highly explosive!!
NOTE!! Hydrogen gas is highly explosive!!!!
Ga(CH3)3 + AsH3
(Trimethal gallium gas) (Arsene gas)
3CH4 + GaAs
(Methane gas) (on the substrate)
If you are British, MOCVD OMCVD!
Dopants are introduced in precisely
Can deposit 1 atomic layer or less!
Source is in here
electron beam probe
to monitor surface film
One period of oscillation growth of one atomic
layer of GaAs (or whatever material)
Mainly useful for research lab experiments. Not efficient for mass production!
Useful for lab experiments & for mass production!
MANY MILLIONS OF
$$$$ FOR BOTH!!!!!
Molecular Beam Expitaxy (MBE)
Metal-Organic Chemical Vapor Deposition (MOCVD)
Differences between MBE and MOCVD
Gases are let into the reactor at high pressure ~ 1 torr
Always done under UHV conditions, with
pressures below 10-8 torr
Becomes saturated with As.
Nucleation of GaAs on the substrate.