Group IV heteroepitaxy on silicon for photonics
- PDF / 414,711 Bytes
- 10 Pages / 584.957 x 782.986 pts Page_size
- 93 Downloads / 238 Views
Silicon emerged as an important substrate material for photonics because of its transparency in the near infrared and its superior planar waveguide properties. Active optoelectronic devices in the infrared wave length regime need semiconductor heterostructures with smaller band gaps as silicon, preferably from the group IV material system. This paper describes fundamental properties of lattice mismatched group IV heterostructures on silicon and their synthesis with epitaxy methods. Special emphasis is given to the aspects of strain management in lattice mismatched device structures and to the realization of metastable non-equilibrium materials. Well-defined strain status is obtained by growth on virtual substrates which consist of silicon substrates with strain relaxed silicon germanium buffer layers. Epitaxy methods at low growth temperatures pushed the synthesis of germanium tin alloys with tin concentrations more than ten times the equilibrium value of about 1%. These achievements pave the way for silicon photonics to efficient light emission and mid infrared operation.
I. INTRODUCTION
Semiconductors in microelectronics and optoelectronics are preferably used as single crystalline materials to get the most precise control on fabrication and operation of the devices. In microelectronics, single crystalline silicon (Si) substrates gained the dominance1 for a bundle of reasons but other semiconductors may perform better for specific functions. The growth of thin single crystalline layers of defined orientation and different chemical compositions on a substrate is called heteroepitaxy. The heteroepitaxy of group IV elements (carbon C, germanium Ge, tin Sn) or of their alloys on Si substrates is especially attractive because these materials of the same chemical group (4 electrons in their outer shell) as Si are not able to create doping centers in the other material. Cross contamination with doping centers is the main problem for an otherwise also very attractive heteroepitaxy system: Group III/V semiconductors on Si. There, small contaminations of 1 ppm creates an unintentional doping of about 5 1016/cm3 in the other material. In Si microelectronics, the SiGe heteroepitaxy found entry into the manufacturing of specific circuits (e.g., microwave circuits with SiGe heterobipolar transistor) or of the source/drain regions of the dominant digital circuits technology, the complementary metal oxide semiconductor circuit. In nearly all high performance processors, the p-type MOS transistors are pushed in their performance by SiGe heteroepitaxy induced elastic stresses. Contributing Editor: Don W. Shaw a) Address all correspondence to this author. e-mail: [email protected] This paper has been selected as an Invited Feature Paper. DOI: 10.1557/jmr.2016.420
The need for heteroepitaxy is even higher in Si photonics because transparent waveguides are combined with optoelectronic devices, which should have a good light matter interaction for light generation, detection, or modulation. Transparency in semiconductors
Data Loading...
