Browsing by Author "Cheng, YC"

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A 1.75GHz inductor-less CMOS low noise amplifier with high-Q active inductor load
(2001)
Yang, JN
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Cheng, YC
;
Hsu, TY
;
Hsu, TR
;
Lee, CY
A 1.75GHz CMOS inductor-less low noise amplifier with high-Q active inductor load using 0.35um. standard CMOS digital process is presented. In this low noise amplifier, the compact tunable high-Q active inductor load is connected to the common-gate configuration to improve the performance of the high power gain, low power consumption and simple matching characteristics. Not using any passive components is to reduce the area of chip and the complexity. HSPICE simulation has been performed to verify the performance of the designed low noise amplifier. It has been shown that the amplifier has a power gain of 24dB(S21), S11 of -31dB, S12 of -38.5dB and S22 of -21.4dB under 3.3V power supply with 9.3mW power consumption around at 1.75GHz center frequency. The experimental chip fabricated occupies 0.057x0.056 mm(2) chip area.
A design of CMOS broadband amplifier with high-Q active inductor
(2003)
Yang, JN
;
Cheng, YC
;
Lee, CY
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A CMOS broadband amplifier with high-Q active inductor using 0.25um CMOS process is presented In this broadband amplifier, the compact high-Q active inductor is connected to the common-gate configuration to improve the performance of the high power gain, wide bandwidth, low power consumption and simple matching characteristics. Not using any passive inductor components is to be reduced the area of chip and the complexity. Advance Design System (ADS) simulator has been performed to verify the performance of the designed broadband amplifier It has been shown that the amplifier has a 20dB(S21) power gain in -3dB bandwidth, S11 of -17dB, S22 of -21 dB and noise figure (NF) of 8dB, under 2.5 V power supply with 18mW power consumption.*
A novel RF CMOS active inductor
(2003-07-01)
Yang, JN
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Cheng, YC
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Lee, CY
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A novel RF CMOS high Q-value active inductor is proposed in this work by using simple cascode RC feedback compensation technique. The performance of this active inductor has maximum Q-value about 1.2E6, inductance value from 3.5 nH to 4.5 nH and 3E-5Omega of minimum total equivalent loss, in the range of 1.2 GHz to 2 GHz.
Alterable temperature-dependent wavelength shifts in (InP)(2)/(GaP)(2) quantum wells
(1998-02-02)
Cheng, YC
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Tai, K
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Chou, ST
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Huang, KF
;
Tu, SL
Alterable temperature-dependent emission wavelength shifts were observed from (InP)(2)/(GaP)(2) short-period superlattices (SPSs) quantum wells grown with different interruption periods. Photoluminescence spectra showed that the peak energy of the SPS samples is inversely proportional to the interruption time conducted between the two consecutive binary growth sequences in the SPS regions. It is believed that a lateral composition modulation occurred during the interruption period which resulted in periodic In-rich and Ga-rich regions in the SPS quantum wells along the growth plane. With the lateral compositional variation, temperature variation can induce a multiaxial strain effect which can either amplify or reduce the temperature-dependent wavelength shift of the SPS quantum wells with different interruption periods. (C) 1998 American Institute of Physics.
Anomalous phosphorus cracker temperature-dependent photoluminescence spectra of InGaP grown by solid source molecular beam epitaxy
(2000-08-01)
Cheng, YC
;
Tai, KC
;
Chou, ST
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光電工程學系
;
Department of Photonics
InGaP grown by solid source molecular beam epitaxy showed lower effective band-gap energy with increasing phosphorus cracker temperature. Anomalous photoluminescence (PL) spectra also indicated that a weaker ordering effect was initiated when the cracker temperature was higher. Since the variation of cracker temperature mainly changed the P-2/P-4 ratio, we believe that the more chemically reactive P-2 incorporates more In into the epilayer. Therefore, InGaP grown under a more Pt-rich condition has a higher In content which results in the lower band-gap energy instead of having an ordering effect.
AuBe Ohmic contacts to p-type ZnTe
(1998-12-10)
Lan, WH
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Lin, WJ
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Cheng, YC
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Tai, K
;
Tasi, CM
Ohmic contacts of AuBe to p-ZnTe show a minimum specific contact resistance of 3.0 x 10(-6) Ohm cm(2) for a p-doping level of 1.6 x 10(19) cm(-3) and at an annealing temperature of 200 degrees C. The beryllium is very effective at improving the electrical properties of p-type contacts to ZnTe.
Deuterium effect on stress-induced leakage current
(1999-04-01)
Lin, BC
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Cheng, YC
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Chin, A
;
Wang, T
;
Tsai, C
We have studied and compared stress-induced leakage current in oxides subjected to H-2 and D-2 annealing. There is not much difference in stress-induced leakage current between thick 70-Angstrom-oxides annealed by these two isotopes. In sharp contrast, an improvement of several-fold in stress-induced leakage current is observed in 27-Angstrom-thick oxides annealed in D-2 ambient compared to that annealed in H-2. The significant improvement in this direct-tunneling oxide may be due to the passivation of intrinsic defects and dangling bonds in a transition SiOx layer.
Formation of self-organized GaN dots on Al0.11Ga0.89N by alternating supply of source precursors
(2004-06-15)
Ke, WC
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Huang, HY
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Ku, CS
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Yen, KH
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Lee, L
The self-organized GaN dot structure is successfully grown on a slightly lattice-mismatched Al0.11Ga0.89N epilayer using flow-rate modulation epitaxy (FME) growth technique. From the variation of dot density with growth temperature, we can observe that the GaN dot growth is controlled predominately by the surface diffusion of Ga adatoms at substrate temperatures below 915degreesC and by re-evaporation at higher temperatures. Because of the special alternating gas supply feature in FME, during the Ga source step, it is the Ga metal that is deposited on the underlying Al0.11Ga0.89N layer. This is because of the large lattice mismatch of 41.8% between the Ga metal (4.51 Angstrom) and Al0.11Ga0.89N (3.18 Angstrom). We consider that the GaN dot growth in our study is mainly through the Volmer-Weber growth mode, not the commonly used Stranski-Krastanow growth mode.
Improving RF CMOS active inductor by simple loss compensation network
(2004-06-01)
Lee, CY
;
Yang, JN
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Cheng, YC
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An RF CMOS active inductor with a novel loss compensation circuit network is proposed. Performance of this active inductor can be improved by adding a novel network, which simultaneously reduces parallel and series losses. Consequently, this technique not only increases Q value, inductance, and operating frequency, but also reduces power consumption and circuit complexity. Simulation results show that better performance indices can be achieved, such as minimum total equivalent loss of 1 mOmega, maximum Q value about 3E5, and inductance value from 20 nH to 45 nH in the RF range of 0.6 GHz to 1.6 GHz. Power dissipation is around 1.76 mW under 2.5 V dc supply voltage.
Microphotoluminescence spectra of hillocks in Al0.11Ga0.89N films
(2004-10-11)
Ke, WC
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Ku, CS
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Huang, HY
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Chen, WC
;
Lee, L
The spatial variation of the optical properties of hillocks in Al0.11Ga0.89N films has been studied by using microphotoluminescence (mu-PL) microscopy. The mu-PL spectrum revealed a strong emission (I-H) at 351 nm from the hillock, besides the near-band-edge emission (I-nbe) at 341 nm. Moreover, the I-H intensity increases significantly and its full width at half maximum decreases from similar to76 to similar to53 meV by probing across the hillock center. These indicated that the hillock structure is a strong emission center. The temperature-dependent mu-PL, measurements showed that the I-H also has the S-shape behavior with a transition temperature of similar to120 K which is lower than that of I-nbe. The redshift of I-H is also smaller than I-nbe. Both indicated that the Al composition in hillocks is lower than the surrounding area. (C) 2004 American Institute of Physics.
Mobility and oxide breakdown behavior in ultra-this oxide with atomically smooth interface
(1998)
Cheng, YC
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Chen, WJ
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Lin, BC
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Tsai, C
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Chin, A
The device performance made by thin gate oxide is related to the oxide thickness uniformity and the interface smoothness. Unfortunately, native oxide roughens the initial surface before thermal oxidation. in this paper, we have designed a leak-tight low-pressure N2O oxidation system, and the native oxide is desorbed in-situ under H-2 environment, Atomically smooth oxide and Si interface of ultra-thill oxides (11-38 Angstrom) were achieved as observed by high-resolutional TEM. Significant mobility enhancement over large gate field is obtained by reducing interface roughness scattering. The oxide reliability is also improved by this smoother interface between Si and oxide.
Optical properties of self-assembled ZnTe quantum dots grown by molecular-beam epitaxy
(2005-02-01)
Yang, CS
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Lai, YJ
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Chou, WC
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Chen, WK
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Lee, MC
The morphology and the size-dependent photoluminescence (PL) spectra of the type-II ZnTe quantum dots (QDs) grown in a ZnSe matrix were obtained. The coverage of ZnTe varied from 2.5 to 3.5 monolayers (MLs). The PL peak energy decreased as the dot size increased. Excitation power and temperature-dependent PL spectra are used to characterize the optical properties of the ZnTe quantum dots. For 2.5- and 3.0-ML samples, the PL peak energy decreased monotonically as the temperature increased. However, for the 3.5-ML sample, the PL peak energy was initially blueshifted and then redshifted as the temperature increased above 40 K. Carrier thermalization and carrier transfer between QDs are used to explain the experimental data. A model of temperature-dependent linewidth broadening is employed to fit the high-temperature data. The activation energy, which was found by the simple PL intensity quenching model, of the 2.5, 3.0, and 3.5 MLs were determined to be 6.35, 9.40, and 18.87 meV, respectively. (C) 2005 American Institute of Physics.
Optimization of short channel effect by arsenic P-Halo implant through polysilicon gate for 0.12uw P-MOSFET
(2000)
Chen, C
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Chang, CY
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Chou, JW
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Huang, CT
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Lin, KC
Excellent PMOS short channel effect is achieved by using high energy, large tilt angle arsenic implant as P-Halo. For the first time, it was found that the tail profile of P-Halo implant through the polysilicon gate, therefore, the channel concentration is modulated not only laterally from gate edge but also vertically from top of the polysilicon gate and it resulted in very flat short channel behavior. The effect of arsenic P-Halo implant was comprehensively studied and well characterized to explain this specific phenomenon. The gate oxide integrity was examined by Q(BD) and it passed the lifetime of 10 years at different conditions of P-Halo implants. Excellent performance of 0.12um PMOSFET is also demonstrated in this work.
Optimization of short channel effect with arsenic halo implant through polysilicon gate
(2001-09-01)
Chen, CM
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Chang, CY
;
Chou, JW
;
Cheng, YC
;
電子工程學系及電子研究所
Excellent p-type metal oxide semiconductor (PMOS) short channel effect is achieved by using a high-energy, large tilt angle arsenic implant as a P-channel halo. For the first time, it was found that the dopant profile of Halo was implanted through the poly-silicon gate. The channel concentration is modulated not only laterally from the gate edge but also vertically from the top of the polysilicon gate and this resulted in very flat short channel behavior. The effect of the arsenic halo implant was comprehensively studied and well characterized to explain this specific phenomenon. The gate-oxide integrity was examined by charge to break down (Q(BD)). Excellent performance of 0.12 mum PMOSFET is also demonstrated in this work.
Ordering reduction in In0.5Ga0.5P grown by solid source molecular beam epitaxy
(1998-02-15)
Cheng, YC
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Tai, KC
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Chou, ST
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Huang, KF
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Tu, SL
In0.5Ga0.5P grown on GaAs substrates with different tilting angles by solid source molecular beam epitaxy (SSMBE) is studied. The results showed that a weak ordering effect still exists in SSMBE grown epilayers with tilted substrates. However, the ordering effect can be drastically reduced by growing In0.5Ga0.5P on a 15 degrees tilted substrate with an InAlP/InGaP superlattices (SL) buffer layer. The In0.5Ga0.5P epilayer grown by this method showed a peak photoluminescence (PL) energy of similar to 1.91 eV at room temperature, which is similar to the reported value for a fully disordered sample. The intensity of the ordering effect is characterized by polarized PL spectroscopy, and the reduction in the ordering intensity is attributed to the elimination of initial surface strain by the SL buffer layer.
Phosphorus-species-induced band-gap anomaly in InGaP grown by solid-source molecular-beam epitaxy
(2001-02-01)
Cheng, YC
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Chi, S
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Huang, KF
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電子物理學系
;
光電工程學系
We report on the growth of InGaP by solid-source molecular-beam epitaxy. It is revealed by photoluminescence (PL) that a lower effective band-gap energy appeared when a higher phosphorus cracker temperature was used. Temperature-dependent PL and polarized photoreflectance (PR) also exhibited a weaker atomic ordering effect when the phosphorus cracker temperature increased. Since the variation of the phosphorus cracker temperature significantly changed the P-2/P-4 ratio, we believe that a more chemically reactive P-2 will not only incorporate more In atoms into the epilayer, but will also bring about a smaller composition fluctuation and weaker ordering effect. Therefore, InGaP grown under a more P-2-rich condition probably has a higher In content which results in a lower band-gap energy instead of the ordering effect.
Reduction of spontaneous surface segregation in (InP)(2)/(GaP)(2) quantum wells grown on tilted substrates
(1999-01-01)
Cheng, YC
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Tai, KC
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Chou, ST
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Huang, KF
;
Lin, WJ
We have studied the growth mechanism of (InP)(2)/(GaP)(2) short-period superlattices (SPS) and In(0.5)Gao(0.5)P quantum wells grown on tilted substrates using solid-source molecular beam epitaxy (SSMBE). Both the (InP)(2)/(GaP)(2) SPS and In0.5Ga0.5P quantum wells show blue shifts of photoluminescence (PL) wavelengths when the substrate's tilting angle is increased. The blue shift is more prominent in the SPS structure than in the In0.5Ga0.5P quantum wells. By comparing FL, polarized PL spectra and transmission electron micrographs, we confirm that the ordering effect exists in both the (InP)(2)/(GaP)(2) SPS and In0.5Ga0.5P quantum wells when the substrate tilt angle is small, and can be greatly reduced when the substrate lilt angle is increased. We believed that the height and density of steps on substrates with larger tilt angles repress the segregation of group III adatoms.
Temperature and annealing effects on photoluminescence spectra of (InAs)(1)/(GaP)(2) superlattices grown by solid-source molecular beam epitaxy
(2000-10-01)
Cheng, YC
;
Chi, S
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Chou, ST
;
Huang, KF
;
電子物理學系
Anomalous variation of photoluminescence (PL) wavelengths with temperature was observed in (InAs)(1)/(GaP)(2) short-period-superlattice (SPS) quantum wells grown by solid-source molecular beam epitaxy with different phosphorus and arsenic cracker temperatures. We believed that the anomalous PL behavior could be attributed to the multi-axial strain effect existed at the abrupt InAs and GaP interfaces in the SPS structure. After rapid thermal anneal (RTA) treatment, the anomalous PL spectra in the low temperature region disappeared but the high temperature PL characteristics remained, which revealed the thermal stability of the (InAs)(1)/(GaP)(2) quantum well structures and its potential in replacing InGaAsP quaternary.