Amorphous oxide semiconductors have attracted attention in electronic device applications because of their high electrical uniformity over large areas, high mobility, and low-temperature process. However, photonic applications of oxide semiconductors are highly limited because of their larger band gap (over 3.0 eV). Here, we propose low band gap zinc oxynitride semiconductors not only because of their high electrical performance but also their high photoresponsivity in the vis-NIR regions. The optical band gap of zinc oxynitride films, which is in the range of 0.95-1.24 eV, could be controlled easily by changing oxygen and nitrogen ratios during reactive sputtering. Band gap tuned zinc oxynitride-based phototransistors showed significantly different photoresponse following both threshold voltage and drain current changes due to variation in nitrogen-related defect sites.
PurposeNeonatal late-onset hypocalcemia is defined as hypocalcemia developed after postnatal 3 days and associated with hypoparathyroidism, high phosphate diets and vitamin D deficiency. We experienced the increment of neonatal late onset hypocalcemia over 1 year. We tried to evaluate the relationship between late onset hypocalcemia and maternal hypovitaminosis D.MethodsThe medical records in the neonates with late-onset hypocalcemia during January 2007 to July 2008 were retrospectively reviewed. Among those patients, 17 paired sera of mothers and neonates had collected. The levels of 25-OH vitamin D (25OHD) and intact parathyroid hormone (iPTH) were measured and were compared with neonate and the mother.ResultsThe mean gestational age was 38+1 weeks, and the mean body weight was 2,980 g. The onset time of hypocalcemia was 5.9 days of age. Most of them (88.2%) were feeding with formula and no one was only breast milk feeding. Of the 17 patients, 13 were born in spring or in winter. The median levels of calcium, phosphorus, alkaline phosphatase, iPTH and 25OHD were 7.0 mg/dL, 8.6 mg/dL, 191.0 U/L, 57.2 pg/mL and 24.0 ng/mL in neonates. The levels of 25OHD of 6 neonates were <20 ng/mL. A total of 16 mothers were considered vitamin D-deficient (<20 ng/mL), and vitamin D insufficient (20<25OHD<30 ng/mL).ConclusionNeonatal late-onset hypocalcemia in our study seems to be influenced by maternal vitamin D deficiency and insufficiency. Sun tanning and vitamin D supplements from winter to spring would be helpful to prevent maternal vitamin D deficiency, one of the causes of neonatal late-onset hypocalcemia.
In this study, we investigated the effects of intense pulsed light (IPL) on the electrical performance properties of zinc oxynitride (ZnON) thin films and thin-film transistors (TFTs) with different irradiation energies. Using the IPL process on the oxide/oxynitride semiconductors has various advantages, such as an ultrashort process time (∼100 ms) and high electrical performance without any additional thermal processes. As the irradiation energy of IPL increased from 30 to 50 J/cm 2 , the carrier concentration of ZnON thin films decreased from 5.07 × 10 19 to 9.96 × 10 16 cm −3 and the electrical performance of TFTs changed significantly, which is optimized at an energy of 40 J/cm 2 (field effect mobility of 48.4 cm 2 V −1 s −1 ). The properties of TFTs, such as mobility, subthreshold swing, and hysteresis, and the stability of the device under negative bias degraded as the irradiation energy increased. This degradation contributed to the change in nitrogen-related bonding states, such as nonstoichiometric Zn x N y and N−N bonding, rather than that of oxygen-related bonding states and the atomic composition of ZnON thin films. Optimization of the IPL process in our results makes it possible to produce high-performance ZnON TFTs very fast without any additional thermal treatment, which indicates that highly productive TFT fabrication can be achieved via this process.
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