Development of Large-Area CdTe/n+-Si Epitaxial Layer-Based Heterojunction Diode-Type Gamma-Ray Detector Arrays
Growth of large area single crystal CdTe layers was studied on <inline-formula> <tex-math notation="LaTeX">$25 \times 25$ </tex-math></inline-formula> mm<sup>2</sup> (211) Si substrates using metalorganic vapor phase epitaxy. High crystalline quality thick crystals with very good material uniformity were obtained. A 2-D monolithic detector array comprising (<inline-formula> <tex-math notation="LaTeX">$20 \times 20$ </tex-math></inline-formula>) pixels was developed and evaluated. Each pixel is <inline-formula> <tex-math notation="LaTeX">$1.12 \times 1.12$ </tex-math></inline-formula> mm<sup>2</sup> size in a 1.17-mm pitch and consists of a p-CdTe/n-CdTe/n<sup>+</sup>-Si heterojunction diode structure, which is isolated from the surrounding pixels by making deep vertical cuts. The detector array exhibited highly uniform and low dark current, typically less than 0.5-<inline-formula> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula>/cm<sup>2</sup> per pixel at an applied reverse bias of 50 V. The spectroscopic performance was separately confirmed by dicing out a small portion from the array which clearly resolved energy peaks from <sup>241</sup>Am gamma isotopes at room temperature. On the other hand, a significant improvement in the detection property was observed by cooling it to −30 °C.
Deposition of ZnO and Gd2O3 by co-sputtering to enable ZnO-Gd2O3 based PIN junction diodes
Abstract In this work we report the fabrication of thin films and p-type/intrinsic/n-type (PIN) diodes based on the intrinsic ZnO-Gd2O3 layer deposited by simultaneously co-sputter ZnO and Gd2O3 from ceramic targets. Nominal percentage of ZnO and Gd2O3 calculated by deposition rate was variated to obtain 3 combinations (55-45, 60-40 and 70-30, first number corresponding to ZnO and second to Gd2O3). Results showed that the resulting ZnO-Gd2O3 intrinsic layer was 1 μm thick, with an amorphous structure as observed by XRD. The layer bandgap escalated from 3.62 eV to 3.98 eV when the amount of Gd2O3 was incremented, exhibiting a transmittance higher than 80% (UV–Vis) and a smooth surface (0.79–2.21 nm), (AFM), size and grain shape showed a combination between ZnO and Gd2O3 (SEM). The best diode (fabricated with 55-45 ZnO-Gd2O3 layer) showed 5 orders of magnitude in rectification, low leakage current of ~10−11 A/mm2 (J-V curves), built-in potential of 1.7 V and carrier concentration in the intrinsic layer of 2 × 1015 cm−3 (C–V measurements). These diodes show promising results for future applications such as in radiation detection, namely neutron and alpha particles detectors.
Cultivated Power: Flowers, Culture, and Politics in the Reign of Louis XIV
Ch. 1. Disorderly flowers Floral seduction: death, sex, and flowers Trading on the power of flowers Ch. 2. Refashioning the culture of flowers in early modern France Curiosity and flowers The sweet society of the curious florists Ch. 3. Cultivating the flower The florists' flowers Unlocking the door to the temple of flora Ch. 4. Cultivating the man The theater of the goddess of flowers Nature into art "Jardin d'Hyver," or flowers in print Ch. 5. Cultivating the king Royal precedents Flowers in the garden of Louis XIV Floral mercantilism Flowers and the "Histoire du Roi" Appendices A. Extract of the inventory by ... Sieur Cottereau of flowering plants and bulbs that he offers to furnish for the gardens of the royal households B. Plants included in Jean Donneau de Vise's Histoire de Louis le Grand