Wen-Yen Lin

High-temperature stability of postgrowth-annealed Al-doped MgxZn1-xO films without the phase separation effect

This study investigates the effects of thermal annealing on Al-doped MgxZn1−xO (AMZO) films. AMZO films were deposited by a radio-frequency magnetron sputtering system using a 4 in. ZnO/MgO/Al2O3 (76/19/5 wt. %) target. This study measures and reports the Hall results, x-ray diffraction (XRD), transmittance, and x-ray photoelectron spectroscopy (XPS) data. XRD results show that the ZnO (002) and MgO2 (002) wurtzite peaks in addition to the (111)-cubic peak disappeared after 1000 °C annealing. This indicates the coexistence of two phases in the as-grown AMZO films rebuilt after higher thermal treatment. The absorption edges of these as-grown AMZO films shifted toward the short wavelength of 323 nm under 80% transmittance, implying that band gaps can be tuned by changing the Mg content of the AMZO layer. The XPS spectra of AMZO films were also used to analyze the composition of the as-grown and annealed AMZO films.

Physical properties of Al-doped MgZnO film grown by RF magnetron sputtering using ZnO/MgO/Al2O3 target

This study investigates the physical properties of Al-doped MgxZn1-xO (AMZO) films. Al-doped MgxZn1-xO films were deposited by radio-frequency (RF) magnetron sputtering system using a 4 inch ZnO/MgO/Al2O3 (76/19/5 wt%) target. This study determined the resulting x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Hall measurement, and transparent performance of the films. XRD results indicate that the diffraction angles of the annealed AMZO film shifted toward the high-angle side, indicating that thermal annealing could relax the compressive strain components in the as-deposited samples. XPS results reveal a high carbon content on the surface of MgxZn1-xO. This may be due to contamination. The average Mg content of the as-grown AMZO is about 19.23 at. % at a depth of 40 nm. The Al-doped MgxZn1-xO film in this study shows high transparency with transmittances over 95 % in the visible region (400 ~ 800nm), and a sharp absorption edge is visible in the UV region due to the Mg content. The Hall measurement of Al-doped MgxZn1-xO films deposited at lower RF power show higher doping concentrations, lower resistivity and higher mobility as a function of the annealing temperature. Experimental results indicate that Al-doped MgxZn1-xO film with 1000 °C annealing contains more oxygen vacancies, which play the role of donor. Oxygen vacancies generate states in the band gap and increase conductivity.

Al-doped MgZnO/p-AlGaN heterojunction and their application in ultraviolet photodetectors

In this study, n-type Al-doped MgxZn1-xO (AMZO) films were deposited onto p-Al0.08Ga0.92N by using radiofrequency magnetron sputtering followed by annealing at 800°C in nitrogen ambient for 60 s. The film was highly transparent and had transmittances exceeding 95% in the visible region and a sharp absorption edge visible in the ultraviolet region. A high leakage current was obtained in the current-voltage (I-V) characteristics of the GMZO/AlGaN n-p junction diode. The AMZO/AlGaN photodetector based on the AMZO film exhibited a dark current of 1.56 μA at Vbias = -3V. The peak responsivity of the photodetector was approximately 200 nm and a cutoff wavelength was observed at approximately 250 nm.

QOS guarantee for wireless LAN with fairness transmission

IEEE 802.11e develops enhanced distributed coordination access (EDCA) and hybrid coordination function (HCF) controlled channel access (HCCA), to enhance the quality of service (QoS) of the original MAC mechanism. However, the priority-based access mechanism can not guarantee QoS requirements in terms of delay and throughput since it is contention-based. In this paper, we propose several schemes that regulate backoff contention window adaptively to achieve more fairness between ACs. The simulation results present the constraint due to agreement level. Moreover, it is demonstrated that the proposed schemes can assign transmission opportunity more fairly than EDCA. Also the proposed schemes really have a performance improvement [1-2].

Decision Support for IPv6 Migration Planning

While confronting the global IPv4 address exhaustion, it is important and crucial for the entire Internet environment to smoothly upgrade to the next generation Internet Protocol, IPv6. In previous years, all the external network services of Taiwan governmental organizations have been upgraded to be IPv6 capable. In this paper, we are concerned about the planning of the IPv6 upgradation for the internal services. Due to a variety of the internal network services, the planning must take account of the network management policy, legacy equipment, monitoring and tracking requirement, Wi-Fi service requirement, the user accountability, the budget, and the scope. Therefore, EMCUD is applied to find the decision rules to help users to develop their IPv6 migration plan.

Comparison of IPv4-over-IPv6 (4over6) and Dual Stack Technologies in Dynamic Configuration for IPv4/IPv6 Address

IPv4 and IPv6 technologies face many challenges on LAN or the Internet such as transition mechanisms. The Internet Engineering Task Force (IETF) proposed a variety of solutions, e.g. Dual stack, IPv6-in-IPv4 (IPv4-IPv6), and IPv4-over-IPv6 (4over6). Clients use manual, stateful, or stateless auto configuration to get IPv6 addresses. Auto configuration with Stateful Dynamic Host Configuration Protocol for IPv6 (DHCPv6) protocol automatically configures IPv6 address through the router into the LAN, which is the best allocation choice. The DHCPv4 and DHCPv6 (DHCP 4o6) server used 4over6 and is considered to generally be the best plan. In this paper, we set up a network communications platform and performed an effectiveness analysis comparing DHCPv4 and DHCPv6 (DHCP 4o6) servers individually with Dual Stack and 4over6 tunnel mechanisms. Experimental routing performances show that the routing path from 7 nodes with Dual Stack was better than 4over6 by 17.329%.

Characterization of Nb-doped MgZnO films grown by a radio-frequency magnetron sputtering system

Niobium-doped MgxZn1-xO (Nb-MZO) mixed oxide films with high transmittance were successfully deposited on sapphire substrates by a radio-frequency (RF) magnetron sputtering using a 4-in ZnO/MgO/NbOx (75/20/5 wt %) target. In this study, the films were analyzed through a Hall test, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmittance. The XRD results showed MgO2 (002) wurtzite peak as well as an MgxZn1-xO (111)-cubic peak. The absorption edges of these Nb-MZO films were located in the UV region, implying that the MgO content of the Nb-MZO layer increased the bandgaps. The XPS spectra of Nb-MZO films were also used to analyze the composition of the as-grown and annealed Nb-MZO films. These results indicate that the Nb-MZO films are ideal for use as transparent contact layers.

Design and Implementation of Health Monitoring System for Solar Panel in IPv6 Network

In traditional, to manage a lot of solar panels in green power plants is very difficult and inefficient. Because one panel set needs a digital power meter, it is very expensive to use the panel to collect all data. To cope with this problem, we proposed a remote monitoring system of solar panels via IPv6 wireless network, in which the parameters of environment and panel voltage would be sent to the Smart Analysis Database System. Then we can monitor the health of the Solar Plant by using the Android mobile platform anywhere and anytime. The administrator not only can use a mobile device to maintain the solar plant and smart home device via IPv6 Network without NAT transformation, but also receive the message immediately when the status of solar panel or home device is abnormal.

A measurement of time synchronization on mobile devices

Android consists of a kernel based on the Linux kernel, with middleware, libraries and APIs written in C and application software running on an application framework which includes Java-compatible libraries. The precision time synchronization protocol daemon (PTPd) is an open source development in C that realizes a PTP. In this work, we were porting the PTPd on android system and measure the performance in network between two mobile devices. Moreover, we demonstrate the feasibility of building an application of time synchronization on android by means of NDK.