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Temperature-gradient metalorganic chemical vapor deposition (MOCVD) was used to deposit InxGa1−xN/GaN multiple quantum well (MQW) structures with a concentration gradient of indium across the wafer. These MQW structures were deposited on low defect density (2×108 cm−2) GaN template layers for investigation of microstructural properties and V-defect (pinhole) formation. Room temperature (RT) photoluminescence (PL) and photomodulated transmission (PT) were used for optical characterization, which show a systematic decrease in emission energy for a decrease in growth temperature. Triple-axis x-ray diffraction (XRD), scanning electron microscopy, and cross-sectional transmission electron microscopy were used to obtain microstructural properties of different regions across the wafer. Results show that there is a decrease in crystal quality and an increase in V-defect formation with increasing indium concentration. A direct correlation was found between V-defect density and growth temperature due to increased strain and indium segregation for increasing indium concentration.

GaN template layer strain effects were investigated on the growth of InGaN/GaN LED devices. Seven period InGaN/GaN multiple quantum well structures were deposited on 5{micro}m and 15{micro}m GaN template layers. It was found that the electroluminescence emission of the 15{micro}m device was red-shifted by approximately 132meV. Triple-axis X-Ray Diffraction and Cross-Sectional Transmission Electron Microscopy show that the 15{micro}m templay layer device was virtually unstrained while the 5{micro}m layer experienced tensile strain. Dynamic Secondary Ion Mass Spectrometry depth profiles show that the 15{micro}m template layer device had an average indium concentration of 11% higher than that of the 5{micro}m template layer device even though the structures were deposited during the same growth run. It was also found that the 15{micro}m layer device had a higher growth rate than the 5{micro}m template layer device. This difference in indium concentration and growth rate was due to changes in thermodynamic limitations caused by strain differences in the template layers.

Composition-graded In x Ga 1− x N Multiple Quantum Wells were deposited on single wafers using a novel growth technique called temperature gradient Organometallic Vapor Phase Epitaxy. A large temperature gradient, 710–785°C, was imposed on 2″ sapphire substrates while growing seven period In x Ga 1− x N Multiple Quantum Well structures. Photoluminescence results show that high quality films, with variations in emission peak from 2.3 to 3.0 eV as a function of position, can be deposited on a single wafer. Photo-modulated transmission was used to determine band-edge optical transition as a means to obtain indium concentration as a function of position. Atomic Force Microscopy was used to image the morphology and relate indium concentrations to film microstructure and optical quality. This is a novel technique that uses a temperature gradient during Organometallic Vapor Phase Epitaxy for depositing variable emission wavelength devices on single wafers.

Three tall, phenotypic female siblings with XY gonadal dysgenesis were found to have short fourth metacarpal bones (bilateral in two and unilateral in the other). Clitoromegaly was observed in the two older siblings, without hirsutism. Bilateral streak gonads were found in all three. A gonadoblastoma was present in the left streak gonad of the youngest, and an adenomatoid tumor in the left streak gonad of the oldest, who was diabetic. Determination of androgens from peripheral and gonadal venous plasma revealed androgen secretion by the streak gonads. On the basis of clinical findings, familial tendency, and androgen secretion from the streak gonads in these patients, it is proposed that the XY gonadal dysgenesis represents a severe from of male pseudohermaphroditism.

Periodontosis is an idiopathic degeneration of the periodontium which results in migration and loss of teeth. The disease begins in the regions of the incisors and first molars. Late in the disease, other areas of the dental arches may be involved. The gingivae are not initially inflamed, and there are no associated systemic abnormalities. Local irritants cannot account for the marked alveolar destruction which leads to the tooth loss. Several heritable syndromes and periodontitis also may be associated with alveolar bone destruction. Periodontosis can be differentiated each of these on the basis of negative laboratory tests, lack of associated anomalies, distinctive pattern of bone loss and timing of onset of gingival inflammation. A family in which periodontosis was present in three of six sibs and in which ichthyosis was segregating independently of periodontosis is reported.