Deposition of single-crystalline compound semiconductor layers (epitaxy) with well-defined optical and electrical properties is the basis for GaAs- and InP-based microelectronics and optoelectronics.
The arsenides & phosphides group is focused on the development of semiconductor layers for optoelectronics. Layers for high-power laser diodes with very high beam quality are available in the wavelength range between 635 nm and 1220 nm. By applying two-step growth processes, structures with gratings for wavelength stabilization are fabricated as well. In cooperation with customers, FBH also develops saturable absorber structures for use in pulsed laser systems.
All these structures require a very good material quality, well-controlled interfaces and precise adjustment of composition and doping of individual semiconductor layers. The development and optimization of deposition processes for the material systems (Al,Ga)As, (Ga,In)(As,P), and (Al,Ga,In)P yielding the required high layer quality are targeted by the group. Using these processes, layer structures are supplied for internal use as well as for external partners and customers.
The epitaxial growth technique is metal organic vapor phase epitaxy (MOVPE) using TMGa, TEGa, TMIn, TMAl, arsine, phosphine, disilane, DMZn, and CBr4 as sources. An accurate control of the purity of these starting materials is essential for the high quality of FBH's layer structures.
A MOVPE systems of the type Aixtron AIX 200/4 with 3×2" or 1×3"/4" capacity is used for exploratory work and production in small volumes. Two production-scale reactors AIX 2800G4 (12×4") are used for larger volumes. The systems are equipped with in situ tools for optical growth control by reflectance and reflectance anisotropy spectroscopy (RAS). FBH extensively uses these tools and closely cooperates with LayTec AG on the development of these techniques.