Herstellung von (GaIn)(NAsP)/GaP Mischkristallsystemen und deren Charakterisierung zur Realisierung eines direkten Halbleiters

The metastable N-containing III/V-compound semiconductor material systems have attracted an immense interest both from a fundamental as well as application point of view. The GaP-based mixed crystalline system is novel in this class of material and especially interesting due to the possibility of realizing monolithic optoelectronic integrated circuits (OIECs) on silicon, since the lattice constant of GaP-substrate is very close to silicon. Though GaP is an indirect semiconductor fundamental band structure can be modified towards totally new optical properties via the incorporation of Indium, Arsenic und Nitrogen. In the present studies the pseudomorphical growth of (GaIn)(NAsP) mixed heterostructures based on GaP-substrate by metal organic vapour phase epitaxy has been investigated over a wide regime of growth parameters in order to optimize the crystalline properties. The crystalline structure has been verified by high-resolution X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Due to the metastability of this material system extreme non-equilibrium growth conditions have to be applied. The penternary mixed crystal reveals a very complex incorporation characteristic for each group V-element. The composition of the (GaIn)(NAsP) material system has been varied systematically in a range that always pseudomorphical deposition is guaranteed on GaP-substrate. In order to study the dependence of the optical properties on the composition, different spectroscopic investigation techniques (photoluminescence (PL), excitation photoluminescence (PLE) and absorption measurement) have been carried out. First results show that the intrinsic optical character can be tailored by the change of composition. For an optimized (GaIn)(NAsP) compound the optoelectronic properties reveal a high photoluminescence efficiency and narrow PL line width even up to room temperature. For the first time optically pumped lasing operation of Ga(NAsP) QWs pseudomorphically grown on GaP substrate have been observed for temperatures up to room temperature. In addition, first electrical injection laser structures have been realized and laser action at low temperatures (80 K) has been verified for the first time. The realized electrical injection laser applying the novel dilute nitride Ga(NAsP)/GaP-material system already at this early stage of development clearly underlines the potential for the integration of III/V-based optoelectronic functionalities using this novel material system to Si substrate in the near future.