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Charge relaxation times. Z. Insepov, V. Ivanov. Glass conductivity. Materials properties. Pore structure Pore diameters – 20 m m Al 2 O 3 +ZnO coatings – 1 m m and 5 m m Aspect ratio -- 40 Materials parameters: Glass: s = 1 10 -17 S/m, e =5.8
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Charge relaxation times Z. Insepov, V. Ivanov
Materials properties Pore structure • Pore diameters – 20 mm • Al2O3+ZnO coatings – 1 mm and 5 mm • Aspect ratio -- 40 Materials parameters: • Glass: s = 110-17 S/m, e=5.8 • Al2O3+ZnO: s = 110-8 S/m, e=6.9 • Air: s = 110-17 S/m, e=1
Al2O3 + ZnO coating resistivity z d r h r = 20 mm d = 1 mm h = 1.6 mm R1 = N R MCP resistance: R = 18-100 MW N = 5106 pores R1=RN = (18-100MW) 5106 = (90-500)1012W
Microscopic model of charge relaxation z r z Dr r A. Spherical symmetry r = 1 mm Al2O3 B. Cylindrical symmetry r = 20 mm Dr= 1 mm Aspect ratio 40 Da,ma,Na – diffusion coeff., mobility, density of carriers (a = e,h) A.K. Jonscher, Principles of semiconductor device operations, Wiley (1960). A.H. Marshak, Proc. IEEE 72, 148-164 (1984). A.G. Chynoweth, J. Appl. Phys. 31, 1161-1165 (1960). R. Van Overstraeten, Solid St. Electronics 13 (1970) 583-608. L.M. Biberman, Proc. IEEE 59, 555-572 (1972). Z. Insepov et al, Phys.Rev. A (2008)
ZnO/Al2O3 alloy relaxation times The current set of emissive coating parameters is not acceptable due to very high curent ~ 20 mA!
MCP Parameters Al2O3+ZnO Table 1: Dielectric constants [1] and resistivities [2] for Al2O3/ZnO ALD films *) DEZ -- Diethylzinc (Zn(CH2CH3)1. Herrmann et al, Proc. of SPIE Vol. 5715 (2005) p.159. 2. Elam et al, J. Electrochem. Soc. 150, pp. G339-G347, 2003.