High Energy Flux Detector Using CdTe P-I-N Layers

1997 ◽  
Vol 487 ◽  
Author(s):  
Madan Niraula ◽  
Tomonori Arakawa ◽  
Toru Aoki ◽  
Yoichiro Nakanishi ◽  
Yoshinori Hatanaka ◽  
...  

Abstractn-and p-type doping of CdTe grown heteroepitaxially on GaAs substrate by radical assisted metal organic chemical vapor deposition technique were studied. n-type doping was studied by the gas phase n-butyliodine doping during the film growth, whereas p-type doping was carried by treating the undoped layers with alkaline metal compound (Na2Te) and excimer laser radiation. Highly conductive n-and p-layers were thus obtained which formed good ohmic contact with aluminum and gold electrodes, respectively. Using this technique, n-and p- layers were formed on intrinsic CdTe substrate to form p-i-n diode. This p-i-n structure showed a good diode characteristics and good sensitivity to X-ray radiation with dark current in the order of nA/mm 2 at room temperature.

2014 ◽  
Vol 896 ◽  
pp. 192-196 ◽  
Author(s):  
Aip Saripudin ◽  
H. Saragih ◽  
Khairurrijal ◽  
Khairurrijal ◽  
Pepen Arifin

Co:TiO2 (cobalt-doped titanium dioxide) thin films have been deposited on the n-type Si (100) substrate at the temperatures range of 325°C 450°C using MOCVD (metal organic chemical vapor deposition) technique. We investigated the effect of growth temperature on the structural and morphological quality of Co:TiO2 thin films. The structure of Co:TiO2 thin films were characterized by XRD while the morphology and the thickness of films were characterized by SEM. The XRD results reveal that all films show the anatase structure and the dominant orientation of anatase phase depends on the growth temperature. The grain size of crystal increases as the growth temperature increases. We also reveal that the growth rate of Co:TiO2 film has a maximum value at the growth temperature of 400°C.


1998 ◽  
Vol 37 (Part 1, No. 8) ◽  
pp. 4595-4602 ◽  
Author(s):  
Aurangzeb Khan ◽  
Mohd Zafar Iqbal ◽  
Umar Saeed Qurashi ◽  
Masafumi Yamaguchi ◽  
Nasim Zafar ◽  
...  

1997 ◽  
Vol 12 (5) ◽  
pp. 1214-1236 ◽  
Author(s):  
Bruce J. Hinds ◽  
Richard J. McNeely ◽  
Daniel B. Studebaker ◽  
Tobin J. Marks ◽  
Timothy P. Hogan ◽  
...  

Epitaxial Tl2Ba2CaCu2O8 thin films with excellent electrical transport characteristics are grown in a two-step process involving metal-organic chemical vapor deposition (MOCVD) of a BaCaCuO(F) thin film followed by a postanneal in the presence of Tl2O vapor. Vapor pressure characteristics of the recently developed liquid metal-organic precursors Ba(hfa)2 • mep (hfa = hexafluoroacetylacetonate, mep = methylethylpentaglyme), Ca(hfa)2 • tet (tet = tetraglyme), and the solid precursor Cu(dpm)2 (dpm = dipivaloylmethanate) are characterized by low pressure thermogravimetric analysis. Under typical film growth conditions, transport is shown to be diffusion limited. The transport rate of Ba(hfa)2 • mep is demonstrated to be stable for over 85 h at typical MOCVD temperatures (120 °C). In contrast, the vapor pressure stability of the commonly used Ba precursor, Ba(dpm)2, deteriorates rapidly at typical growth temperatures, and the decrease in vapor pressure is approximately exponential with a half-life of ∼9.4 h. These precursors are employed in a low pressure (5 Torr) horizontal, hot-wall, film growth reactor for growth of BaCaCuO(F) thin films on (110) LaAlO3 substrates. From the dependence of film deposition rate on substrate temperature and precursor partial pressure, the kinetics of deposition are shown to be mass-transport limited over the temperature range 350–650 °C at a 20 nm/min deposition rate. A ligand exchange process which yields volatile Cu(hfa)2 and Cu(hfa) (dpm) is also observed under film growth conditions. The MOCVD-derived BaCaCuO(F) films are postannealed in the presence of bulk Tl2Ba2CaCu2O8 at temperatures of 720–890 °C in flowing atmospheres ranging from 0–100% O2. The resulting Tl2Ba2CaCu2O8 films are shown to be epitaxial by x-ray diffraction and transmission electron microscopic (TEM) analysis with the c-axis normal to the substrate surface, with in-plane alignment, and with abrupt film-substrate interfaces. The best films exhibit a Tc = 105 K, transport-measured Jc= 1.2 × 105 A/cm2 at 77 K, and surface resistances as low as 0.4 mΩ (40 K, 10 GHz).


2009 ◽  
Vol 1198 ◽  
Author(s):  
Neeraj Nepal ◽  
M. Oliver Luen ◽  
Pavel Frajtag ◽  
John Zavada ◽  
Salah M. Bedair ◽  
...  

AbstractWe report on metal organic chemical vapor deposition growth of GaMnN/p-GaN/n-GaN multilayer structures and manipulation of room temperature (RT) ferromagnetism (FM) in a GaMnN layer. The GaMnN layer was grown on top of a n-GaN substrate and found to be almost always paramagnetic. However, when grown on a p-type GaN layer, a strong saturation magnetization (Ms) was observed. Ms was almost doubled after annealing demonstrating that the FM observed in GaMnN film is carrier-mediated. To control the hole concentration of the p-GaN layer by depletion, GaMnN/p-GaN/n-GaN multilayer structures of different p-GaN thickness (Xp) were grown on sapphire substrates. We have demonstrated that the FM depends on the Xp and the applied bias to the GaN p-n junction. The FM of these multilayer is independent on the top GaMnN layer thickness (tGaMnN) for tGaMnN >200 nm and decreases for tGaMnN < 200 nm. Thus the room temperature FM of GaMnN i-p-n structure can also be controlled by changing Xp and tGaMnN in the GaMnN i-p-n structures.


1995 ◽  
Vol 378 ◽  
Author(s):  
J. C. Chen ◽  
Z. C. Huang ◽  
Bing Yang ◽  
H. K. Chen ◽  
K. J. Lee

AbstractA study was carried out to characterize the deep impurities in AlxGa1-x As grown by metal-organic chemical vapor deposition (MOCVD) using different carrier gases. Since AlxGai1-x As is very sensitive to any impurities, especially moisture and oxygen, in the growth process, the concentration of impurities in AlxGai1-xAs can serve as a measure of the purity of carrier gases. The undoped AlGaAs layers grown by using H2 have n-type background concentrations from 3×1015 to 10×1015/cc. The concentrations of oxygen-related traps (Ec−0.53 and 0.7 eV) are 0.2−9×1013 and 3.4−5×1014/cc for Pd- and Li-purified H2, respectively. Low-temperature photoluminescence (PL) measurements show better PL efficiency in samples grown by using Pd- purified H2. AlxGa1-xAs grown by using N2 is p-type (p∼6×1016/cc) with an oxygen-related trap and two hole traps. The concentration of oxygen-related trap is more than one order of magnitude higher than that of AlGaAs using Pd-purified H2. The memory effect due to impurities from carrier gas left in source materials is also studied.


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