Distributed contact flip chip InGaN/GaN blue LED; comparison with conventional LEDs

Genc, M.
Sheremet, V.
Elci, M.
Egin, G.
Islamoglu, S.
Gür, Emre
Muzafferoglu, N.
This paper presents high performance, GaN/InGaN-based light emitting diodes (LEDs) in three different device configurations, namely Top Emitting (TE) LED, conventional Flip Chip (FC) and Distributed Contact (DC) FC. Series resistances as low as 1.1 Omega have been obtained from FC device configurations with a back reflecting ohmic contact of Ni/Au/RTA/Ni/Ag metal stack. A small shift has been observed between electroluminescence (EL) emissions of TE LED and the FC LEDs. In addition, FWHM value of the EL emission of DCFC LED has shown the minimum value of 160 meV (26.9 nm). Furthermore, DCFC LED configuration has shown the highest quantum efficiency and power output, with 330 mW at 500 mA current injection, compared to that of traditional wire bonded TE LEDs and the conventional FC LEDs.


Hybrid connection of RF MEMS and SMT components in an impedance tuner
Unlu, Mehmet; Topalli, Kagan; Atasoy, Halil Ibrahim; Demir, Şimşek; Aydın Çivi, Hatice Özlem; Akın, Tayfun (Elsevier BV, 2010-01-01)
This paper presents a systematic construction of a model for a hybrid connected RF MEMS and SMT components in a reconfigurable impedance tuner. The double stub hybrid impedance tuner which employs a high number of MEMS switches is selected to demonstrate the feasibility of the connections. In the hybrid tuner, MEMS switches are actuated with DC bias signals, where SMT resistors de-couple RF from the DC lines. The hybrid tuner is realized in two steps, where the MEMS impedance tuner is fabricated on a glass ...
Active clamped ZVS forward converter with soft-switched synchronous rectifier for high efficiency, low output voltage applications
Acik, A; Cadirci, I (Institution of Engineering and Technology (IET), 2003-03-01)
The analysis, design, and implementation of an active clamped ZVS forward converter equipped with a soft-switched synchronous rectifier (ACFC-SR), proposed for high-efficiency low output voltage DC-DC converter applications, is presented. The converter efficiency is maximised due to soft switching of the main, active clamp, synchronous rectifier, and freewheeling MOSFET switches. The operating principles of the ACFC-SR are analysed in detail, and the converter performance is compared with that of alternativ...
Custom integrated circuit design for ultrasonic therapeutic CMUT array
Maadi, Mohammad; Bayram, Barış (Springer Science and Business Media LLC, 2015-04-01)
This paper presents the design of a highly flexible and programmable transmit beam-former ASIC using a high voltage (HV) 0.35 mu m CMOS technology to be flip-chip bonded to a 4 x 4 CMUT array for ultrasound therapeutic applications. However, proposed IC can be used as a transmitter circuitry in color Doppler 3D imaging applications. In our proposed chip, each CMUT element is provided by an 8-bit shift register, an 8-bit comparator, a one-shot circuit with adjustable pulse width, a programmable pulse train g...
Mutual coupling of printed elements on a cylindrically layered structure using closed-form Green's functions
Acar, R. C.; Dural, G. (EMW Publishing, 2008-01-01)
A hybrid method to calculate mutual coupling of electric or magnetic current elements on a cylindrically layered structure using closed-form Green's functions is presented. When rho = rho' and phi is not very close to phi', closed-form Green's functions are employed in the calculation of MoM matrix entries. When both rho = rho' and phi = phi', series representation of the spectral domain Green's functions do not converge, therefore closed-form Green's functions can not be employed. In that case MoM matrix e...
Tunable dual-frequency RF MEMS rectangular slot ring antenna
Topalli, Kagan; Erdil, Emre; Aydın Çivi, Hatice Özlem; Demir, Şimşek; Koç, Seyit Sencer; Akın, Tayfun (Elsevier BV, 2009-12-01)
This paper presents the design, fabrication, and measurement of a novel, tunable, dual frequency rectangular slot antenna using RF MEMS technology. The antenna tuning is achieved by electrostatically actuated RF MEMS variable capacitors on a stub. Two different capacitor structures are implemented on the antenna: cantilever type and fixed-fixed beam type. The latter one is not sensitive to the stress on the structural layer and its measurement results agree well with the simulation results. Each antenna is ...
Citation Formats
M. Genc et al., “Distributed contact flip chip InGaN/GaN blue LED; comparison with conventional LEDs,” SUPERLATTICES AND MICROSTRUCTURES, pp. 9–13, 2019, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/63065.