Electrical properties of isotype and anisotype ZnO/4H-SiC heterojunction diodes

Abstract

Electrical properties of isotype n-ZnO/n-4H-SiC and anisotype n-ZnO/p-4H-SiC heterojunction diodes have been investigated and compared. The influence of the electron concentration in ZnO on diode parameters has been also examined. ZnO/4H-SiC heterojunctions fabricated by atomic layer deposition of ZnO on bulk 4H-SiC substrates show highly rectifying behaviour with leakage current values lower than 10−11A. The isotype heterojunction diodes demonstrate better electrical properties than anisotype heterojunction diodes, in particular lower values of ideality factors (1.13–1.2 as compared to 1.36–1.52), series resistance (5–7 Ω as compared to 66–80 Ω), capacitance (2 times lower, at 0 V), and built-in voltage (1.13–1.42 V as compared to 1.78–1.87 V). Diodes with higher doped ZnO layers show lower series resistance and built-in voltage as compared to diodes with lower doped ZnO layers. Isotype as well as anisotype heterojunction diodes demonstrate a strong influence of UV-light illumination on reverse current-voltage characteristics; however, isotype structures with n-4H-SiC show lower reverse current under cyan (λ = 488 nm) light illumination as to anisotype structures with p-type 4H-SiC, due to the lack of donor-acceptor pair absorption. This makes ZnO/4H-SiC isotype heterojunction diodes more suitable for visible-blind UV photodetectors than the anisotype ones.

Temperature-Dependent Photoluminescence of ZnO Thin Films Grown on Off-Axis SiC Substrates by APMOCVD

“…This may result in the formation of ZnO layers with lower defect density and misfit dislocations, as compared to ZnO films grown on sapphire, Si, GaAs, or ScAlMgO 4 [ 48 ]. In addition, the integration of ZnO and SiC technologies is an extremely important step from the practical point of view, since the ZnO/SiC structure has a great potential to be used as isotype or anisotype heterojunction diodes [ 49 ]. In this context, it is expected to reach the control of the properties of the ZnO layers by using appropriate vicinal SiC substrates.…”

Introductory Chapter: Overview of ZnO Based Nano Materials and Devices

“…Many other properties of ZnO allow variety of applications. These applications include photovoltaics, LEDs, photodetectors, and microelectromechanical systems (MEMs) [8][9][10][11][12].…”

“…The ZnO material is being used for many optoelectronic based devices applications. These devices applications include the varistors, sensors [13,[56][57][58][59], optical wave guides, UV light emitters [60], LEDs [61], micro-electro-mechanical systems [12], spin electronics [62], solar energies [63], p-n junctions [64], field effect and emissions [65][66][67], displays [68], acoustic waves [69], and solar cells [6]. ZnO nanorods [53].…”

Review of Recent Advances of ZnO Nanowires Based Sensors

“…These characteristic properties attracted several researchers to improve the electrical and optical properties of ZnO thin films. Other physical properties opened a wide range of applications in photovoltaics, LEDs, photodetectors in UV spectral range, and microelectromechanical systems (MEMs) [9,10,11,12,13]. The ZnO crystalline structure exists as wurtzite and zinc blende as shown in Figure 1, which led it as a perfect polar symmetry along the hexagonal axis, which is responsible for a number of the physical and chemical properties, including piezoelectricity and spontaneous polarization [14].…”