A 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode array

We report a 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode (APD) array. The mean breakdown voltage of the APD was 57.9 V and the standard deviation was less than 0.1 V. The mean dark current was /spl sim/2 and /spl sim/300 nA, and the standard deviation was /spl sim/0.19 and /spl sim/60 nA at unity gain (V/sub bias/ = 13.5 V) and at 90% of the breakdown voltage, respectively. External quantum efficiency was above 40% in the wavelength range from 1.0 to 1.6 /spl mu/m. It was /spl sim/57% and /spl sim/45% at 1.3 and 1.55 /spl mu/m, respectively. A bandwidth of 13 GHz was achieved at low gain.     

Long-wavelength In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As large-area avalanche photodiodes and arrays

Large-area (500-/spl mu/m diameter) mesa-structure In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiodes (APDs) are reported. The dark current density was /spl sim/2.5/spl times/10/sup -2/ nA//spl mu/m/sup 2/ at 90% of breakdown; low surface leakage current density (/spl sim/4.2 pA//spl mu/m) was achieved with wet chemical etching and SiO/sub 2/ passivation. An 18 /spl times/ 18 APD array with uniform distributions of breakdown voltage, dark current, and multiplication gain has also been demonstrated. The APDs in the array achieved 3-dB bandwidth of /spl sim/8 GHz at low gain and a gain-bandwidth product of /spl sim/120 GHz.     

Metal-semiconductor-metal (MSM) photodetectors fabricated on MOCVD grown Hg/sub 1-x/Cd/sub x/Te

The fabrication of the first metal-semiconductor-metal photodetectors on Hg/sub 1-x/Cd/sub x/Te is reported using MOCVD grown layers on GaAs substrates. An epitaxial CdTe overlayer has been incorporated in the device structure for the enhancement of Schottky barrier characteristics. The interdigitated devices (2.3 mu m electrode width, 3.3 mu m spacing) exhibited a breakdown voltage of -60 V and responsivities of more than 1.0 A/W at a wavelength of 1.3 mu m and bias voltage of 40 V. Over the range of bias voltage examined, the dark leakage current of the detectors was dependent on the choice of contact metal, with minimum values of 10 nA at <1 V for Pt/CdTd/Hg/sub 1-x/Cd/sub x/Te.<>     

A novel InGaP/Al/sub x/Ga/sub 1-x/As/GaAs CEHBT

A new and interesting InGaP/Al/sub x/Ga/sub 1-x/As/GaAs composite-emitter heterojunction bipolar transistor (CEHBT) is fabricated and studied. Based on the insertion of a compositionally linear graded Al/sub x/Ga/sub 1-x/As layer, a near-continuous conduction band structure between the InGaP emitter and the GaAs base is developed. Simulation results reveal that a potential spike at the emitter/base heterointerface is completely eliminated. Experimental results show that the CEHBT exhibits good dc performances with dc current gain of 280 and greater than unity at collector current densities of J/sub C/=21kA/cm/sup 2/ and 2.70/spl times/10/sup -5/ A/cm/sup 2/, respectively. A small collector/emitter offset voltage /spl Delta/V/sub CE/ of 80 meV is also obtained. The studied CEHBT exhibits transistor action under an extremely low collector current density (2.7/spl times/10/sup -5/ A/cm/sup 2/) and useful current gains over nine decades of magnitude of collector current density. In microwave characteristics, the unity current gain cutoff frequency f/sub T/=43.2GHz and the maximum oscillation frequency f/sub max/=35.1GHz are achieved for a 3/spl times/20 /spl mu/m/sup 2/ device. Consequently, the studied device shows promise for low supply voltage and low-power circuit applications.     

High breakdown voltage (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P/InGaAs quasi-enhancement-mode pHEMT with field-plate technology

A high breakdown voltage and a high turn-on voltage (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P/InGaAs quasi-enhancement-mode (E-mode) pseudomorphic HEMT (pHEMTs) with field-plate (FP) process is reported for the first time. Between gate and drain terminal, the transistor has a FP metal of 1 /spl mu/m, which is connected to a source terminal. The fabricated 0.5/spl times/150 /spl mu/m/sup 2/ device can be operated with gate voltage up to 1.6 V owing to its high Schottky turn-on voltage (V/sub ON/=0.85 V), which corresponds to a high drain-to-source current (I/sub ds/) of 420 mA/mm when drain-to-source voltage (V/sub ds/) is 3.5 V. By adopting the FP technology and large barrier height (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P layer design, the device achieved a high breakdown voltage of -47 V. The measured maximum transconductance, current gain cutoff frequency and maximum oscillation frequency are 370 mS/mm, 22 GHz , and 85 GHz, respectively. Under 5.2-GHz operation, a 15.2 dBm (220 mW/mm) and a 17.8 dBm (405 mW/mm) saturated output power can be achieved when drain voltage are 3.5 and 20 V. These characteristics demonstrate that the field-plated (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P E-mode pHEMTs have great potential for microwave power device applications.     

60-GHz high power performance In/sub 0.35/Al/sub 0.65/As-In/sub 0-35/Ga/sub 0.65/As metamorphic HEMTs on GaAs

We report on a double-pulse doped, double recess In/sub 0.35/Al/sub 0.65/As-In/sub 0.35/Ga/sub 0.65/As metamorphic high electron mobility transistor (MHEMT) on GaAs substrate. This 0.15-/spl mu/m gate MHEMT exhibits excellent de characteristics, high current density of 750 mA/mm, extrinsic transconductance of 700 mS/mm. The on and off state breakdown are respectively of 5 and 13 V and defined It gate current density of 1 mA/mm. Power measurements at 60 GHz were performed on these devices. Biased between 2 and 5 V, they demonstrated a maximum output power of 390 mW/mm at 3.1 V of drain voltage with 2.8 dB power gain and a power added efficiency (PAE) of 18%. The output power at 1 dB gain compression is still of 300 mW/mm. Moreover, the linear power gain is of 5.2 dB. This is to our knowledge the best output power density of any MHEMT reported at this frequency.     

A 183 GHz f/sub T/ and 165 GHz f/sub max/ regrown-emitter DHBT with abrupt InP emitter

Small-area regrown emitter-base junction InP/In-GaAs/InP double heterojunction bipolar transistors (DHBT) using an abrupt InP emitter are presented for the first time. In a device with emitter-base junction area of 0.7 /spl times/ 8 /spl mu/m/sup 2/, a maximum 183 GHz f/sub T/ and 165 GHz f/sub max/ are exhibited. To our knowledge, this is the highest reported bandwidth for a III-V bipolar transistor utilizing emitter regrowth. The emitter current density is 6/spl times/10/sup 5/ A/cm/sup 2/ at V/sub CE,sat/ = 1.5 V. The small-signal current gain h/sub 21/ = 17, while collector breakdown voltage is near 6 V for the 1500-/spl Aring/-thick collector. The emitter structure, created by nonselective molecular beam epitaxy regrowth, combines a small-area emitter-base junction and a larger-area extrinsic emitter contact, and is similar in structure to that of a SiGe HBT. The higher f/sub T/ and f/sub max/ compared to previously reported devices are achieved by simplified regrowth using an InP emitter and by improvements to the regrowth surface preparation process.     

547-GHz f/sub t/ In/sub 0.7/Ga/sub 0.3/As-In/sub 0.52/Al/sub 0.48/As HEMTs with reduced source and drain resistance

We fabricated 30-nm gate pseudomorphic channel In/sub 0.7/Ga/sub 0.3/As-In/sub 0.52/Al/sub 0.48/As high electron mobility transistors (HEMTs) with reduced source and drain parasitic resistances. A multilayer cap structure consisting of Si highly doped n/sup +/-InGaAs and n/sup +/-InP layers was used to reduce these resistances while enabling reproducible 30-nm gate process. The HEMTs also had a laterally scaled gate-recess that effectively enhanced electron velocity, and an adequately long gate-channel distance of 12nm to suppress gate leakage current. The transconductance (g/sub m/) reached 1.5 S/mm, and the off-state breakdown voltage (BV/sub gd/) defined at a gate current of -1 mA/mm was -3.0 V. An extremely high current gain cutoff frequency (f/sub t/) of 547 GHz and a simultaneous maximum oscillation frequency (f/sub max/) of 400 GHz were achieved: the best performance yet reported for any transistor.     

Submicron gate Si/sub 3/N/sub 4//AlGaN/GaN-metal-insulator-semiconductor heterostructure field-effect transistors

We present the characteristics of a quarter-micron gate metal-insulator-semiconductor heterostructure field-effect transistor (MISHFET) with Si/sub 3/N/sub 4/ film as a gate insulator. A detailed comparison of the MISHFET and an identical geometry HFET shows them to have the same radio frequency (RF) power gain and cut-off frequency, while the MISHFET has much lower gate-leakage currents and higher RF powers at operating frequencies as high as 26 GHz. The MISHFET gate-leakage currents are well below 100 pA at gate bias values from -10 V to +8 V. At zero gate bias, the drain saturation current is about 0.9 A/mm and it increases to 1.2 A/mm at +8 V gate bias. The output RF power of around 6 W/mm at 40 drain bias was found to be frequency independent in the range of 2 to 26 GHz. This power is 3 dB higher than that from HFET of the same geometry. The intrinsic cutoff frequency is /spl sim/63 GHz for both the HFET and the MISHFET. This corresponds to an average effective electron velocity in the MISHFET channel of 9.9/spl times/10/sup 6/ cm/s. The knee voltage and current saturation mechanisms in submicron MISHFETs and heterostructure field-effect transistors (HFET) are also discussed.     

InGaAs/InP composite collector heterostructure bipolar transistors

A high speed bipolar transistor with high breakdown voltage BV/sub CEO/ is described. The structure uses a composite collector of InGaAs and InP. A common emitter gain of 65 is obtained with a base doping of 7*10/sup 19/ cm/sup -3/ and a breakdown voltage in excess of 10 V. The f/sub T/=64 GHz was reached at a collector-emitter voltage of 2 V and a current density of 52 kA/cm/sup 2/. The potential of this structure for very high speed applications is demonstrated by the extracted intrinsic transit time of 0.4 ps.<>     

DC and RF characteristics of E-mode Ga/sub 0.51/In/sub 0.49/P-In/sub 0.15/Ga/sub 0.85/As pseudomorphic HEMTs

The DC and RF characteristics of Ga/sub 0.49/In/sub 0.51/P-In/sub 0.15/Ga/sub 0.85/As enhancement- mode pseudomorphic HEMTs (pHEMTs) are reported for the first time. The transistor has a gate length of 0.8 /spl mu/m and a gate width of 200 /spl mu/m. It is found that the device can be operated with gate voltage up to 1.6 V, which corresponds to a high drain-source current (I/sub DS/) of 340 mA/mm when the drain-source voltage (V/sub DS/) is 4.0 V. The measured maximum transconductance, current gain cut-off frequency, and maximum oscillation frequency are 255.2 mS/mm, 20.6 GHz, and 40 GHz, respectively. When this device is operated at 1.9 GHz under class-AB bias condition, a 14.7-dBm (148.6 mW/mm) saturated power with a power-added efficiency of 50% is achieved when the drain voltage is 3.5 V. The measured F/sub min/ is 0.74 dB under I/sub DS/=15 mA and V/sub DS/=2 V.     

High-performance MIM capacitor using ALD high-k HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectrics

For the first time, we successfully fabricated and demonstrated high performance metal-insulator-metal (MIM) capacitors with HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectric using atomic layer deposition (ALD) technique. Our data indicates that the laminate MIM capacitor can provide high capacitance density of 12.8 fF//spl mu/m/sup 2/ from 10 kHz up to 20 GHz, very low leakage current of 3.2 /spl times/ 10/sup -8/ A/cm/sup 2/ at 3.3 V, small linear voltage coefficient of capacitance of 240 ppm/V together with quadratic one of 1830 ppm/V/sup 2/, temperature coefficient of capacitance of 182 ppm//spl deg/C, and high breakdown field of /spl sim/6 MV/cm as well as promising reliability. As a result, the HfO/sub 2/-Al/sub 2/O/sub 3/ laminate is a very promising candidate for next generation MIM capacitor for radio frequency and mixed signal integrated circuit applications.     

High-responsivity high-gain In/sub 0.53/Ga/sub 0.47/As-InP quantum-well infrared photodetectors grown using metal-organic vapor phase epitaxy

We report the growth and fabrication of bound-to-bound In/sub 0.53/Ga/sub 0.47/As-InP quantum-well infrared photodetectors using metal-organic vapor phase epitaxy. These detectors have a peak detection wavelength of 8.5 /spl mu/m. The peak responsivities are extremely large with R/sub pk/=6.9 A/W at bias voltage V/sub b/=3.4 V and temperature T=10 K. These large responsivities arise from large detector gain that was found to be g/sub n/=82 at V/sub b/=3.8 V from dark current noise measurements at T=77 K and g/sub p/=18.4 at V/sub b/=3.4 V from photoresponse data at T=10 K. The background-limited temperature with F/1.2 optics is T/sub BLIP/=65 K for 0相似文献   

Evidence and understanding of ALD HfO/sub 2/-Al/sub 2/O/sub 3/ laminate MIM capacitors outperforming sandwich counterparts

Metal-insulator-metal capacitors with atomic-layer-deposited HfO/sub 2/-Al/sub 2/O/sub 3/ laminated and sandwiched dielectrics have been compared, for the first time, for analog circuit applications. The experimental results indicate that significant improvements can be obtained using the laminated dielectrics, including an extremely low leakage current of 1/spl times/10/sup -9/ A/cm/sup 2/ at 3.3V and 125/spl deg/C, a high breakdown electric field of /spl sim/3.3MV/cm at 125/spl deg/C, good polarity-independent electrical characteristics, while retaining relatively high capacitance density of 3.13 fF//spl mu/m/sup 2/ as well as voltage coefficients of capacitance as low as -80 ppm/V and 100 ppm/V/sup 2/ at 100 kHz. The underlying mechanism is likely due to alternate insertions of Al/sub 2/O/sub 3/ layers that reduce the thickness of each HfO/sub 2/ layer, hereby efficiently inhibiting HfO/sub 2/ crystallization, and blocking extensions of grain boundary channels from top to bottom as well as to achieve good interfacial quality.     

Turn-on voltage investigation of GaAs-based bipolar transistors with Ga/sub 1-x/In/sub x/As/sub 1-y/N/sub y/ base layers

The fundamental lower limit on the turn on voltage of GaAs-based bipolar transistors is first established, then reduced with the use of a novel low energy-gap base material, Ga/sub 1-x/In/sub x/As/sub 1-y/N/sub y/. InGaP/GaInAsN DHBTs (x/spl sim/3y/spl sim/0.01) with high p-type doping levels (/spl sim/3/spl times/10/sup 19/ cm/sup -3/) and dc current gain (/spl beta//sub max//spl sim/68 at 234 /spl Omega///spl square/) are demonstrated. A reduction in the turn-on voltage over a wide range of practical base sheet resistance values (100 to 400 /spl Omega///spl square/) is established relative to both GaAs BJTs and conventional InGaP/GaAs HBTs with optimized base-emitter interfaces-over 25 mV in heavily doped, high dc current gain samples. The potential to engineer turn-on voltages comparable to Si- or InP-based bipolar devices on a GaAs platform is enabled by the use of lattice matched Ga/sub 1-x/In/sub x/As/sub 1-y/N/sub y/ alloys, which can simultaneously reduce the energy-gap and balance the lattice constant of the base layer when x/spl sim/3y.     

A 160-GHz f/sub T/ and 140-GHz f/sub MAX/ submicrometer InP DHBT in MBE regrown-emitter technology

We report a 0.7/spl times/8 /spl mu/m/sup 2/ InAlAs-InGaAs-InP double heterojunction bipolar transistor, fabricated in a molecular-beam epitaxy (MBE) regrown-emitter technology, exhibiting 160 GHz f/sub T/ and 140 GHz f/sub MAX/. These initial results are the first known RF results for a nonselective regrown-emitter heterojunction bipolar transistor, and the fastest ever reported using a regrown base-emitter heterojunction. The maximum current density is J/sub E/=8/spl times/10/sup 5/ A/cm/sup 2/ and the collector breakdown voltage V/sub CEO/ is 6 V for a 1500-/spl Aring/ collector. In this technology, the dimension of base-emitter junction has been scaled to an area as low as 0.3/spl times/4 /spl mu/m/sup 2/ while a larger-area extrinsic emitter maintains lower emitter access resistance. Furthermore, the application of a refractory metal (Ti-W) base contact beneath the extrinsic emitter regrowth achieves a fully self-aligned device topology.     

Study of reverse dark current in 4H-SiC avalanche photodiodes

Temperature-dependent current-voltage (I-V) measurements have been used to determine the reverse dark current mechanisms in 4H-SiC avalanche photodiodes (APDs). A pn junction vertical mesa structure, passivated with SiO/sub 2/ grown by plasma enhanced chemical vapor deposition, exhibits predominate leakage current along the mesa sidewall. Similar APDs, passivated by thermal oxide, exhibit lower dark current before breakdown; however, when the temperature is higher than 146/spl deg/C, an anomalous dark current, which increases rapidly with temperature, is observed. This current component appears to be eliminated by the removal of the thermal oxide. Near breakdown, tunneling is the dominant dark current mechanism for these pn devices. APDs fabricated from a pp/sup -/n structure show reduced tunneling current. At room temperature, the dark current at 95% of breakdown voltage is 140 fA (1.8 nA/cm/sup 2/) for a 100-/spl mu/m diameter APD. At a gain of 1000, the dark current is 35 pA (0.44 /spl mu/A/cm/sup 2/).     

RF, DC, and reliability characteristics of ALD HfO/sub 2/-Al/sub 2/O/sub 3/ laminate MIM capacitors for Si RF IC applications

High-performance metal-insulator-metal capacitors using atomic layer-deposited HfO/sub 2/-Al/sub 2/O/sub 3/ laminate are fabricated and characterized for RF and mixed-signal applications. The laminate capacitor can offer high capacitance density (12.8 fF//spl mu/m/sup 2/) up to 20 GHz, low leakage current of 4.9/spl times/10/sup -8/ A/cm/sup 2/ at 2 V and 125/spl deg/C, and small linear voltage coefficient of capacitance of 211 ppm/V at 1 MHz, which can easily satisfy RF capacitor requirements for year 2007 according to the International Technology Roadmap for Semiconductors. In addition, effects of constant voltage stress and temperature on leakage current and voltage linearity are comprehensively investigated, and dependences of quadratic voltage coefficient of capacitance (/spl alpha/) on frequency and thickness are also demonstrated. Meanwhile, the underlying mechanisms are also discussed.     

High-speed photoconductive switch based on low-temperature GaAs transferred on SiO/sub 2/-Si substrate

In this letter, we report high-speed photoconductive switches based on low-temperature (LT) grown GaAs on Si substrate. Epitaxially grown LT GaAs was separated from its substrate, transferred on an SiO/sub 2/-coated Si substrate and integrated with a transmission line. The 10/spl times/20-/spl mu/m/sup 2/ switches exhibit high breakdown voltage and low dark currents (<10/sup -7/ A at 100 V). The photoresponse at 810 nm shows electrical transients with /spl sim/0.55-ps full-width at half-maximum and /spl sim/0.37-ps decay time, both independent on the bias voltage up to the tested limit of 120 V. The photoresponse amplitude increases up to /spl sim/0.7 V with increased bias and the signal bandwith is /spl sim/500 GHz. The freestanding LT GaAs switches are best suited for ultrafast optoelectronic testing since they can be placed at virtually any point on the test circuit.     

Improvement of voltage linearity in high-/spl kappa/ MIM capacitors using HfO/sub 2/-SiO/sub 2/ stacked dielectric

It is demonstrated that the voltage coefficients of capacitance (VCC) in high-/spl kappa/ metal-insulator-metal (MIM) capacitors can be actively engineered and voltage linearity can be significantly improved maintaining high capacitance density, by using a stacked insulator structure of high-/spl kappa/ and SiO/sub 2/ dielectrics. A MIM capacitor with capacitance density of 6 fF/spl mu/m/sup 2/ and quadratic VCC of only 14 ppm/V/sup 2/ has been demonstrated together with excellent frequency and temperature dependence (temperature coefficients of capacitance of 54 ppm /spl deg/C) as well as low leakage current of less than 10 nA/cm/sup 2/ up to 4 V at 125 /spl deg/C.