Zn-doped InGaAs Base Heterojunction Bipolar Transistors Grown by Low Pressure Metal Organic Chemical Vapor Deposition

High performance InP/InGaAs heterojunction bipolar transistors(HBTs) have been widely used in high-speed electronic devices and optoelectronic integrated circuits. InP-based HBTs were fabricated by low pressure metal organic chemical vapor deposition(MOCVD) and wet chemical etching. The sub-collector and collector were grown at 655 ℃ and other layers at 550 ℃. To suppress the Zn out-diffusion in HBT, base layer was grown with a 16-minute growth interruption. Fabricated HBTs with emitter size of 2.5×20 μm~2 showed current gain of 70~90, breakdown voltage(BV_(CE0))>2 V, cut-off frequency(f_T) of 60 GHz and the maximum relaxation frequency(f_(MAX)) of 70 GHz.

A Multi-Finger Si_(1-x)Ge_x/Si Heterojunction Bipolar Transistor for Wireless Power Amplifier Applications

A large area multi-finger configuration power SiGe HBT device(with an emitter area of about 880μm~2)was fabricated with 2μm double-mesa technology.The maximum DC current gain β is 214.The BV_(CEO) is up to 10V,and the BV_(CBO) is up to 16V with a collector doping concentration of 1×10~(17)cm~(-3) and collector thickness of 400nm.The device exhibits a maximum oscillation frequency f_(max) of 19.3GHz and a cut-off frequency f_T of 18.0GHz at a DC bias point of I_C=30mA and V_(CE)=3V.MSG(maximum stable gain)is 24.5dB,and U(Mason unilateral gain)is 26.6dB at 1GHz.Due to the novel distribution layout,no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.

Design and Fabrication of Power Si1-xGex/Si Heterojunction Bipolar Transistor for Wireless Power Amplifier Applications

A multi-finger structure power SiGe HBT device （with an emitter area of about 166μm^2） is fabricated with very simple 2μm double-mesa technology. The DC current gain β is 144.25. The B-C junction breakdown voltage reaches 9V with a collector doping concentration of 1 × 10^17cm^-3 and a collector thickness of 400nm. Though our data are influenced by large additional RF probe pads, the device exhibits a maximum oscillation frequency fmax of 10.1GHz and a cut-off frequency fτ of 1.8GHz at a DC bias point of IC=10mA and VCE = 2.5V.

Surface Disorder of GaN Irradiated by Highly Charged Arq+-Ions

Surface damage of gallium nitride films irradiated by Arq+ (6 ≤ q ≤ 16) ions at room temperature is studied by the atomic force microscopy. It is found that when charge state exceeds a threshold value, significant swelling was turned into obvious erosion in the irradiated region. The surface change of the irradiated region strongly depends on the charge state and ion fluence. On the other hand, surface change is less dependent on the kinetic energy nearly in the present experimental range (120 keV≤ Ek ≤ 220 keV). For q ≤ 14, surface of the irradiated region iscovered with an amorphous layer, rough and bulgy. A step-up appears between the irradiated and un-irradiated region. Moreover, the step height and the surface roughness are functions of the ion dose and charge state...

Synthesis and Properties of Carbazole Main Chain Copolymers with Oxadiazole Pendant toward Bipolar Polymer Host: Tuning the HOMO/LUMO Level and Triplet Energy

Three new carbazole copolymers, poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-3,6-diyl)s (P1), poly(9-(2,5-diarene-[1,3,4]oxadiazole)-2, 7-carbazole-alt-9-(2-ethylhexyl)-3, 6-carbazole-diyl)s (P2), and poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-2,7-diyl)s (P3), were synthesized by the Suzuki coupling reaction

Solution-processable highly efficient yellow- and red-emitting phosphorescent organic light emitting devices from a small molecule bipolar host and iridium complexes

A bipolar transport compound, 2,5-bis(4-(9-(2-ethylhexyl)-9H-carbazol-3-yl) phenyl)-1,3,4-oxadiazole (CzOXD), incorporating both electron-and hole-transport functionalities, was synthesized and fully characterized by H-1 NMR, C-13 NMR, elemental analysis and mass spectrometry. Its thermal, electrochemical, electronic absorption and photoluminescent properties were studied

Multifunctional bipolar triphenylamine/oxadiazole derivatives: highly efficient blue fluorescence, red phosphorescence host and two-color based white OLEDs

Two simple triphenylamine/oxadiazole derivatives were synthesized and fully characterized; their multifunctionality as highly efficient non-doped blue fluorescence, excellent red phosphorescent host and single-doped two-color based white OLEDs has been demonstrated.

Order-disorder transition in eicosylated polyethyleneimine comblike polymers

Order-disorder transition (ODT) behavior in eicosylated polyethyleneimine (PEI20C) comblike polymer obtained by grafting n-eicosyl group on polyethyleneimine backbone was systematically investigated by the combination of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy as well as solid-state high resolution nuclear magnetic resonance (NMR) spectroscopy. DSC investigations showed two obvious transitions, assigned to the transitions (1) from orthorhombic to hexagonal and (2) from hexagonal to amorphous phase, respectively. These transitions are induced by the variations of alkyl side chain conformation and packing structure with temperature changing, which consequently lead to the destruction of original phase equilibrium. The ODT behavior can also be confirmed by spectroscopic methods like WAXD, FTIR and NMR. The ordered structure and the transition behavior of the alkyl side chains confined by the PEI backbone are obviously different from those of pristine normal alkanes. The transition mechanism of ODT and the origin of the phase transition behavior in PEI20C comblike polymer were discussed in detail in this paper.

Polymer light-emitting diodes based on a bipolar transporting luminescent polymer

A soluble electroluminescent polymer containing hole-deficient triphenylamine and electron-deficient oxadiazole units in the main chains has been designed and studied. The design is based on the consideration that the triphenylamine group possesses good hole-transporting property and the oxadiazole unit is known to be of electron-transporting character. Because of the good bipolar transporting performance, the brightness and electroluminescent efficiency are significantly improved and the turn-on voltage is reduced compared with a similar polymer without the electron-deficient oxadiazole units in the main chains. For a device with configuration ITO/PEDOT/polymer/CsF/Al, a maximum brightness of 3600 cd m(-2) and a maximum luminescent efficiency of 0.65 cd A(-1) (quantum efficiency of 0.3%) were obtained in the polymer with oxadiazole units, about 15 times brighter and 15 times more efficient than the corresponding polymer without oxadiazole units.