Metal Organic Vapor Phase Epitaxy
Three different MOVPE growth kits are installed in the MOVPE lab. They were manufactured by the AIXTRON AG, Aachen. The reactors have an enormous flexibility with respect to the number of different source chemicals useable and the carrier gases and their mixtures. The first two are models AIX 200 (year of manufacture 1988 and 1989) and are a both heated by an infra red heating system.
The single reactor system is used for the epitaxy of phase change alloys containing Ge, Sb, In and Te. The reactor is equipped with an optical measurement system EpiR-M-TT (Laytec), which uses white light and can detect the reflected light in the range between 500 nm (2.48 eV) and 1600 nm (0.77 eV). Different measurement modes allow spectroscopic measurements over a certain range as well as time resolved measurements at a given wavelength. Additionally the temperature of the wafer surface is measured using emissivity corrected pyrometry.
In the double reactor system, the two reactors are positioned on top of each other and are equipped with substrate rotation. They are used for the deposition of conventional III/V materials. In the upper reactor, InAs lateral nanowires are deposited selectively in trenches for a future CMOS based on high mobility channel materials. In the lower reactor, InAs quantum dots encompassed in GaAs nanowires are produced for future single photon emission.
The other MOVPE system is a model AIX 200/4 RFS (year of manufacture 1998, rebuilt for nitride growth 2002), with two reactors side by side which are heated with an RF heating system and are equipped with substrate rotation. This system is used for III nitride growth. A separation plate is inserted in the gas inlet of the reactor with which the ammonia and the group III sources are injected separately into the reactor. The special feature of this system is the possibility to switch between two different inlet configurations: the conventional in which ammonia is injected closer to the substrate surface and the inverted - here the ammonia is injected closer to the reactor ceiling. One reactor is reserved for the deposition of layers such as HEMT structures, LEDs and the investigation of new growth templates with respect to their suitability for nitrides. The other is reserved for the selective area growth of emitter type nanostructures such as nanopyramids encompassed in N- and p-doped GaN. Both structure types are employed in few photon emitter devices. Both reactors are equipped with in situ analysis: an EpiR-TT-DA system, LayTec with a wavelength regime from 250 - 825 nm and two optical sensors.