GaN/Al(Ga)N heterostructures: MBE growth, electronic properties and polarization fields

The demand of higher and higher storage density in digital data processing applications lead in the last decade to an increased interest in the development of injection lasers operating at short wavelengths. The group III-nitrides has revealed to be the most successful class of semiconductors for optoelectronic applications for wavelengths from 200 to 650 nm. Beside this, the nitrides are moving first promising steps also in the field of radiofrequency devices: AlGaN/GaN HEMTs grown on seminsulating SiC show very high power density at frequencies up to 50 GHz and an excellent thermal and chemical stability. The aim of this work was to achieve experimentally the knowledge of the energy band scheme along several nitride heterostructures and the surfaces electronic properties, thus providing a set of basic parameters needed for the design of heterostructure devices. The first step for the realization of GaN/Al(Ga)N heterostructures and for the determination of their band scheme was the optimization of the GaN and AlGaN deposition by means of MBE on 6H-SiC substrates. To this phase belonged the preparation of the substrate, a systematic change of the growth parameters and a consequent control of structural, optical and electrical properties by means of different experimental techniques (XRD, PL, AFM, Hall). (orig.)SIGLEAvailable from TIB Hannover: RA 831(3781) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman