In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As abrupt double-heterojunction bipolar transistors

In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As n-p-n abrupt double-heterojunction bipolar transistors grown by molecular beam epitaxy (MBE) have been realized for the first time. DC current gains in excess of 300 have been measured on devices operated in the emitter-up configuration. DC current gains around 50 are obtained on device structures with Be+ implanted extrinsic base regions operated in the emitter-down configuration. The carrier injection and collection behavior of the abrupt InGaAs/InAlAs heterojunctions is discussed.     

Characteristics of metal-ferroelectric-insulator-semiconductor structure using Sr0.8Bi2.2Ta2O9 and Sr0.8Bi2.2Ta2O9-BaZrO3 for ferroelectric gates

Characteristics of BaZrO₃ (BZO) modified Sr_0.8Bi_2.2Ta₂O₉ (SBT) thin films fabricated by sol-gel method on HfO₂ coated Si substrates have been investigated in a metal-ferroelectric-insulator-semiconductor (MFIS) structure for potential use in a ferroelectric field effect transistor (FeFET) type memory. MFIS structures consisting of pure SBT and doped with 5 and 7 mol% BZO exhibited memory windows of 0.81, 0.82 and 0.95 V with gate voltage sweeps between −5 and +5 V, respectively. Leakage current density levels of 10⁻⁸ A/cm² for BZO doped SBT gate materials were observed and attributed to the metallic Bi on the surface as well as intrinsic defects and a porous film microstructure. The higher than expected leakage current is attributed to electron trapping/de-trapping, which reduces the data retention time and memory window. Further process improvements are expected to enhance the electronic properties of doped SBT for FeFET.     

Beat-frequency between measurements between C12O216and C12O218lasers

Several beat frequencies in the range below 6 GHz have been measured using a C¹²O2¹⁶laser and a C¹²O2¹⁸laser operating on several pairs of closely spaced lines in the 9.3-μm region.     

Some new FIR laser lines of optically pumped12CH316OH,12CH316OD, and12CH3I,12CH3Br,12CD2Cl2absorption spectroscopy of water and acetonitrile

The wavelength, polarization, and output power of several lines of the optically pumped CW FIR¹²CH3¹⁶OH (methanol) and¹²CH3¹⁶OD (1-D deuterated methanol), methyl iodide, methyl bromide, and deuterated methylene chloride lasers have been determined. In addition to lines already reported in the literature, seven strong lines have been observed. Optimum performance of the laser system is achieved by means of an improved coupling of the CO2pump power into the resonator and extraction of the FIR power from the resonator. Measurements on the power absorption coefficient of water using the laser indicate thatalpha(bar{nu})rises to almost 1100 Np ċ cm^-1at 170 cm^-1, and then shows a gradual fall with an increase in frequency. A strong temperature dependence of the 200 cm^-1peak inalpha(bar{nu})is predicted, with a decrease in the frequency of maximum power absorption coefficient with an increase in temperature. The range of measurements for acetonitrile is extended to lower frequencies so as to overlap with those determined from other millimeter wave techniques. For highly power-absorbing liquids,alpha(bar{nu})is estimated to be within ± 5 percent.     

Laser4F3/2→4I9/2and4F3/2→4I13/2transitions in KY(WO4)2:Nd3+

We report the observation of lasing at 0.9137 μm and 1.3545 μm in neodymium-doped KY(WO4)2at 77 K. Transition cross sections, fluorescent line width, and branching ratios are given.     

Al0.25In0.75P/Al0.48In0.52As/Ga0.35In 0.65As graded channelpseudomorphic HEMT's with high channel-breakdown voltage

A new Al_0.25In_0.75P/Al_0.48In_0.52 As/Ga_0.35In 0_.65As pseudomorphic HEMT where the InAs mole fraction of the Ga_1-xIn_xAs channel was graded (x=0.53→0.65→0.53) is described. The modification of the quantum well channel significantly improved breakdown characteristics. In addition, use of an Al_0.25In_0.75P Schottky layer increased the Schottky barrier height. Devices having 0.5 μm gate-length showed g_m of 520 mS/mm and I_max of 700 mA/mm. The gate-drain (BV_g-d) and source-drain (BV_d-s ) breakdown voltages were as high as -14 and 13 V, respectively. An f_T of 70 GHz and f_max of 90 GHz were obtained     

选频~(14)CO_2-~(12)CO_2同位素激光器

我们研制了一台~(14)CO_2-~(12)CO_2同位素激光器,测量到激光谱线80条,其中40条是~(14)CO_200°1-(10°0,02°0)_I带的激光跃迁谱线,强线输出功率达4.0W以上;实验还观察到同位素的竞争效应,发现即使~(14)CO_2成份低于~(12)CO_2,其激光辐射仍占优势.     

Waveguide In0.53Ga0.47As-In0.52Al0.48As avalanche photodiode

A high-speed waveguide In_0.53Ga_0.47As-In_0.52Al_0.48 As separate absorption, charge, and multiplication avalanche photodiode suitable for operation at 1.55 μm has been demonstrated, a unity-gain bandwidth of 27 GHz was achieved with a gain-bandwidth product of 120 GHz     

An In0.52Al0.48As/n+-In0.53Ga0.47As MISFET with a modulation-doped channel

A heterostructure metal-insulator-semiconductor field-effect transistor (MISFET) with a modulation-doped channel is proposed. In this device, a very thin undoped subchannel is located between the undoped wide-bandgap insulator and a thin heavily doped channel. In the depletion mode of operation, electron transport takes place along the heavily doped channel. When the device enters the accumulation mode of operation, electrons pile up against the heterointerface in the high-mobility undoped subchannel. This results in markedly improved transport characteristics at the onset of accumulation. The concept is demonstrated in the In_0.52Al_0.48As/In_0.53 Ga_0.47As system on InP. A 1.5-μm-gate-length MISFET shows a unity current-gain cutoff frequency of 37 GHz     

Temporal stability of circulating current in thin film Tl2Ba2CaCu2O8 and YBa2Cu3O7

The temporal stability of trapped transport current in annular thin film Tl₂Ba₂CaCu₂O₈ (TBCCO) and YBa₂Cu₃O₇ (YBCO) wafers has been accurately measured and has been found to be of suitable quality for the stringent requirements of nuclear magnetic resonance (NMR) magnets. No detectable decay, to the limit of the experimental apparatus (2*10^-14 Ω), was detected in those wafers with transport current at or below the critical current density J_c. The critical current density, as previously determined from 12 μm meander lines, was confirmed in a wafer with a width of 1.9 cm. The profile of trapped magnetic field resulting from induced current was modeled in order to assess its effect on the uniformity of an NMR magnet     

Doubly strainedIn0.41Al0.59As/n+-In0.65Ga0.35As HFET with high breakdown voltage

An In_0.41Al_0.59As/n⁺-In_0.65 Ga_0.35As HFET on InP was designed and fabricated, using the following methodology to enhance device breakdown: a quantum-well channel to introduce electron quantization and increase the effective channel bandgap, a strained In_0.41Al_0.59As insulator, and the elimination of parasitic mesa-sidewall gate leakage. The In_0.65Ga_0.35As channel is optimally doped to N_D=6×10¹⁸ cm^-3. The resulting device (L_g=1.9 μm, W_g =200 μm) has f_t=14.9 GHz, f_max in the range of 85 to 101 GHz, MSG=17.6 dB at 12 GHz V_B=12.8 V, and I_D(max)=302 mA/mm. This structure offers the promise of high-voltage applications at high frequencies on InP     

Sm^3＋掺杂的镉铝硅酸盐玻璃的光谱特性

用高温固相反应法合成了掺钐的镉铝硅酸盐玻璃,室温下测量了样品的透射光谱、发射光谱、激发光谱和近红外发射光谱。研究了玻璃中钐离子的光谱性质,在488nmAr离子激光激发下,该玻璃在1202．5nm、193．5nm及957．5nm有强近红外发射。     

Ga0.4In0.6As/Al0.55In0.45As pseudomorphic modulation-doped field-effect transistors

High-performance pseudomorphic Ga0.4In0.6As/ Al0.55In0.45As modulation-doped field-effect transistors (MODFET's) grown by MBE on InP have been fabricated and characterized. DC transconductances as high as 271, 227, and 197 mS/mm were obtained at 300K for 1.6-µm and 2.9-µm gate-length enhancement-mode and 2-µm depletion-mode devices, respectively. An average electron velocity as high as 2.36 × 10⁷cm/s has been inferred for the 1.6-µm devices, which is higher than previously reported values for 1-µm gate-length Ga0.47In0.53As/Al0.48In0.52As MODFET's. The higher bandgap Al0.55In0.45As pseudomorphic barrier also offers the advantages of a larger conduction-band discontinuity and a higher Schottky barrier height.     

High-frequency submicrometerAl0.48In0.52As/In0.53Ga0.47As heterostructure bipolar transistors

The high speed scaling of an Al_0.48In_0.52As/In_0.53Ga_0.47 As submicrometer heterostructure bipolar transistor (HBT) is presented. Transistors with emitter dimensions of 0.5×11 and 3.5×3.5 μm² exhibit unity current-gain cutoff frequencies of 63 and 70 GHz, respectively. Emitter current density greater than 3.3×10⁵ A/cm² is demonstrated in a submicrometer AlInAs/InGaAs HBT. The analysis shows that the device speed is limited by the parasitic collector charging time     

An In0.53Ga0.47As/Si3N4n-channel inversion mode MISFET

We describe the operation of an n-channel inversion-mode In0.53Ga0.47As MISFET with a Si3N4insulating layer. This device exhibits a transconductance of 2 mS/mm, which represents an order of magnitude improvement over previously reported In0.53Ga0.47As MISFET results.     

Ion-implanted In0.53Ga0.47As/In0.52Al0.48As lateral PNP transistors

Lateral PNP transistors have been realized for the first time in the (In,Ga)As/(In,Al)As heterostructure material system. Be ion implantation has been used to form the emitter and collector junctions. A current gain of 3.8 is obtained up to 200 µA of collector current for devices with a 1.5 µm electrical base width. A hole diffusion length of 2 µm in the (In,Ga)As is estimated.     

MetamorphicIn0.53Ga0.47As/In0.52Al0.48As HEMTs on germanium substrates

We report for the first time the successful epitaxial growth and processing of high-performance metamorphic high electron mobility transistors (HEMTs) on Ge substrates, with a transconductance of 700 mS/mm and a saturation channel current of 650 mA/mm. To reduce parasitic capacitances due to the conductive substrate, a dry etch method based on CF₄ and O₂ reactive ion etching (RIE) is developed for selective substrate removal. Devices with 0.2 μm gate length display an increase of the extrinsic cut-off frequency f_T from 45 GHz before, to 75 GHz after substrate removal, whereas the maximum oscillation frequency f_max increases from 68 GHz to 95 GHz. Based on this excellent rf performance level, in combination with the highly selective thinning process, we think that Ge as a sacrificial substrate is a promising candidate for the integration of thinned individual HEMTs with passive circuitry on low-cost substrates. This could result in low-cost advanced hybrid systems for mass-market millimeter wave applications     

Buried-Pt gate InP/In0.52Al0.48As/In0.7Ga0.3As pseudomorphic HEMTs

InP-based high electron mobility transistors (HEMTs) were fabricated by depositing Pt-based multilayer metallization on top of a 6-nm-thick InP etch stop layer and then applying a post-annealing process. The performances of the fabricated 55-nm-gate HEMTs before and after the post-annealing were characterized and were compared to investigate the effect of the penetration of Pt through the very thin InP etch stop layer. After annealing at 250 °C for 5 min, the extrinsic transconductance (G_m) was increased from 1.05 to 1.17 S/mm and Schottky barrier height was increased from 0.63 to 0.66 eV. The unity current gain cutoff frequency (f_T) was increased from 351 to 408 GHz, and the maximum oscillation frequency (f_max) was increased from 225 to 260 GHz. These performance improvements can be attributed to penetration of the Pt through the 6-nm thick InP layer, and making contact on the InAlAs layer. The STEM image of the annealed device clearly shows that the Pt atoms contacted the InAlAs layer after penetrating through the InP layer.     

60-GHz pseudomorphicAl0.25Ga0.75As/In0.28Ga0.72As low-noise HEMTs

V-band low-noise planar-doped pseudomorphic (PM) InGaAs high electron mobility transistors (HEMTs) were fabricated with an indium mole fraction of 28% in the InGaAs channel. A device with 0.15-μm T-gate achieved a minimum noise figure of 1.5 dB with an associated gain of 6.1 dB at 61.5 GHz     

Possibility ofNd1.9Ba1.1Cu3O7+δ andPr1.14Ba1.86Cu3O7-δsingle crystals for insulator in high-speed superconductingcircuits

Dielectric properties of both Nd_1.9Ba_1.1Cu ₃O_7+δ (NBCO-213) and Pr_1.14Ba_1.86Cu₃O_7-δ (Pr-rich PBCO) single crystals have been examined at low temperature. These materials have good lattice matching to high-T_c superconductors (HTS), but they are conductive at room temperature. Below 80 K, they are insulators with low dielectric constants, ε _τ below 25, and low dielectric loss tan δ below 0.1 at 100 kHz. The value of ε_τ is suitable for insulators in integrated circuits using strip line widths of 10 μm order, providing short delay time, no excitation of surface wave, and low radiation loss. The value of tan δ is comparable to loss of superconducting surface resistance above 100 GHz. These results indicate the applicability for the insulator layers in multilayer superconducting electronic devices such as Single Flux Quantum (SFQ) circuits operated at high speed