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Fe-doped semi-insulating InP epitaxial layers were grown by low-pressure organometallic vapor phase epitaxy with tertiarybutylphosphine (TBP), triethylindium (TEI) and iron pentacarbonyl [Fe(CO)5] as the reactant gases. The growth was performed by varying the growth rate, growth pressure and V/III ratio. The epitaxial layers were characterized by optical microscopy, secondary ion mass spectrometry, double crystal x-ray diffraction and current-voltage measurements. Semi-insulating InP epitaxial layers with specular surface morphology and low defect density were obtained at TBP partial pressure higher than 0.38 torr. A premature reaction between TEI and TBP was observed which presumably formed TEI:TBP adducts and/or polymers. As a result, the growth rate of Fe-doped semi-insulating InP layers grown at low pressure with TBP in our reactor decreased by 35% as the V/III ratio was increased from 15 to 46. Electrical measurements on these layers showed that the resistivity varied from 1.7×107 to 4×108 Ω cm as the V/III ratio was increased from 15 to 46. The resistivity of TBP-grown materials is comparable to that of PH3-grown materials over a measurement temperature range of 25–110 °C. Selective growth and surface planarization of Fe-doped InP grown with TBP and trimethylindium on patterned etched mesas were achieved.

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Influence of pulp condition on the accuracy of an electronic foramen locator in posterior teeth: an in vivo study Abstract: The aim of this study was to assess, in vivo, the accuracy of the NovApex  electronic foramen locator in determining working length (WL) in vital and necrotic posterior teeth. The NovApex  was used in 144 canals: 35 teeth with vital pulps (68 canals) and 42 teeth with necrotic pulps (76 canals). WL was measured with the NovApex  locator and confirmed using the radiographic method. Differences between electronic and radiographic measurements ranging between 0.0 and 0.4 millimeters were classified as acceptable; differences equal to or greater than 0.5 millimeter were considered unacceptable. Pearson's chi-square test was used to assess the influence of pulp condition on the accuracy of NovApex  (α = 0.05). Regardless of pulp condition, differences between electronic and radiographic WL measurements were acceptable in 73.61% of the canals. No statistically significant differences in accuracy were observed when comparing vital and necrotic canals (p > 0.05). There were 38 unacceptable measurements. In none of these cases was the file tip located beyond the radiographic apex; in 32, it was located short of the NovApex  measurement. Pulp condition had no significant effect on the accuracy of NovApex  .

High power VCSEL arrays have experienced rapid growth and development. In this paper, we review the unique properties of VCSELs and present the progress that is making them very attractive for high power laser applications. INTRODUCTIONOver the past five to ten years, high-power vertical-cavity surface emitting laser (VCSEL) arrays have experienced rapid growth and development. Traditionally known for low-power applications such as short reach datacom links, recent work has shown VCSELs to be capable of high efficiencies and very high output powers. Coupled with that are the unique properties of VCSELs, such as circularly symmetric output beam, narrow spectral linewidth, and a low-cost fabrication model; high-power VCSEL arrays are becoming increasingly attractive for high-power laser applications such as solid-state pumping, welding, illumination, and printing, to name a few.The leading diode laser technology currently supplied to the marketplace is the edge-emitting laser (EEL), which boasts very high conversion efficiencies (60% -70%), and can be stacked to achieve kW-class power levels. While current VCSEL array efficiencies are typically <50%, other properties lend to potential improved system level performance and lower system level costs. This paper reviews the benefits of VCSELs and presents the current state of the art performance from VCSEL arrays.

High quality Fe-doped semi-insulating InP epitaxial layers were grown by low-pressure organometallic vapor phase epitaxy using tertiarybutylphosphine (TBP) and triethylindium (TEI) as the reactant sources. Semi-insulating InP epitaxial layers with specular surface morphology and low defect density were obtained at TBP partial pressure higher than 0.38 Torr. Electrical measurements on these layers showed the resistivity of TBP-grown materials to be comparable to that of PH3-grown materials over a measurement temperature range of 25 to 110 °C. A premature reaction between TEI and TBP was observed upstream from the substrate in which things such as TEI:TBP adducts and/or polymers could have been formed. This reaction occurred under low pressure, high gas flow conditions which effectively suppressed analogous reactions for TEI:PH3. As a result, the growth rate of Fe-doped semi-insulating InP layers grown at low pressure with TBP in our reactor decreased by 35% as the V/III ratio was increased from 15 to 46.