June 1987

Document Type


Degree Name



Dept. of Applied Physics


Oregon Graduate Center


Presented here are the growth and characterization results of a study of the semiconductors GaAs, InP, and InGaAs. The methylbased organometallic sources trimethylindium and trimethylgallium were used in an atmospheric pressure organometallic vapor phase epitaxy (OMVPE) reactor. Evaluation of this growth technique was conducted with an eye toward optical applications, particularly lasers and photodetectors. The OGC OMVPE system is described here, including the parameters used for growing 150+ epilayers. GaAs and InP epilayers were obtained with 300 K Hall mobilities of 6480 and 4820 cm2/Vs, and photoluminescence (PL) peak full width at half maximum values of 12 and 10 meV respectively at 77 K. While some optoelectronic devices require p-type InP and InGaAs, little use has been made of magnesium as a dopant. A study of Mg-doped InP is reported here. Mg offers an attractive alternative to zinc for abrupt junctions because of its low diffusivity. PL peaks seen at 1.0 and 1.3 eV from InP:Mg at 77 K suggest several Mg incorporation mechanisms beyond the simple MgIn substitutional acceptor. The growth of InGaAs epilayers of various compositions is discussed. An empirical study documents the extent in the present system of the parasitic reaction which depletes trimethylindium prior to the growth zone. InGaAs epilayers grown lattice-matched to InP are described. For these, Hall mobilities of 9000 and 26,500 cm2/Vs at 300 K and 77 K respectively were achieved. The optical absorption coefficient was measured over a broad energy range for In[subscript 1-x] Ga[subscript x]As with compositions between x = 0.45 and x = 0.51, at 10, 77, and 300 K. The absorption coefficient rises abruptly to 6000 cm[superscript -1] just above the bandgap and increases gradually to 30,000 cm[superscript -1] at 1.5 eV. Motivation for this work was provided by the scarcity of published optical absorption data for InGaAs. An intrinsic InGaAs defect was found by PL at 71 K giving emission near 0.7 eV. A variety of methods were used to characterize this defect, and these results are presented.





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