摘要:

AlGaAs/GaAs double‐heterojunction high electron mobility transistors (DHHEMTs) grown by low‐pressure organometallic vapor phase epitaxy are reported in this communication. The magnetic field‐dependent Hall effect measurement was used to characterize the sheet carrier density and electron mobility of the two‐dimensional electron gas (2‐DEG). At 77 K the sheet carrier density and the electron mobility were 1.38×1012cm−2and 52 900 cm2/V s, respectively, in a DHHEMT structure with an undoped Al0.28Ga0.72As spacer layer of 120 A˚, while they were 7.12×1011cm−2and 65 100 cm2/V s, respectively, in a comparable single‐heterojunction HEMT structure. DHHEMT’s with 0.5‐&mgr;m‐gate length and 75‐&mgr;m‐gate width have been fabricated with dc saturation current of 500 mA/mm and dc transconductance of 250 mS/mm. These results are comparable to those produced with molecular‐beam epitaxy.

ISSN:0021-8979    

DOI:10.1063/1.345244

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Phosphorus (P) coimplantation raises the optimum annealing temperature, providing maximum sheet carrier concentration in Si‐implanted GaAs active layers. 3×1013cm−2coimplanted P raises the optimum annealing temperature for channel layers from 920 to 990 °C, the same temperature for contact layers. Photoluminescence measurement reveals that this is due to suppression of GaAsand SiAsacceptor generations up to about 1000 °C by P coimplantation. These features indicate that P coimplantation helps to achieve GaAs integrated circuits with high performance.

ISSN:0021-8979    

DOI:10.1063/1.345245

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The evanescent wave excitation of a long‐range surface polariton in a silver film is treated including the effects of the finite width of the incident laser beam and the slow spatial variation of the amplitude of the surface polariton. The theoretical results of the antiresonance characteristics in the angular response of the reflectivity are compared with the available experimental observations.

ISSN:0021-8979    

DOI:10.1063/1.345246

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The density‐of‐states around midgapg(E) of undoped amorphous silicon (a‐Si:H) has been determined by measuring the space‐charge‐limited photocurrent (SCLPC) ofa‐Si:H Schottky diodes under blue light (&lgr;=450 nm) illumination. In this novel technique, a single type of photogenerated carrier is utilized as the source of space charge to dispense with highly doped layers required in the conventional space‐charge‐limited current (SCLC) technique. Conditions for the uniform formation of space charge are discussed and checked by the satisfaction of a scaling law for samples with different thicknesses. Theg(E) deduced from the SCLPC is found to be similar to that from the SCLC technique.

ISSN:0021-8979    

DOI:10.1063/1.346086

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new deep level transient spectroscopy technique is suggested which allows the deep level parameters to be obtained from a single temperature scan. Using large ratiot2/t1of the measurement gate positionst1andt2and analyzing the steep high‐temperature side of the peak, it is demonstrated that the deep level activation energy can be determined with high accuracy.

ISSN:0021-8979    

DOI:10.1063/1.345192

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

GaInAs/InP quantum wells have been grown on (001) InP substrates by atmospheric pressure organometallic vapor‐phase epitaxy with well widths ranging from a few monolayers to 100 A˚. The interface quality and the epilayer thickness were examined using x‐ray diffraction spectroscopy and transmission electron microscopy. The layers were found to be very uniform with both interfaces apparently free of defects. In addition, for a nominal 8 A˚ quantum well, a (110) high‐resolution cross‐sectional lattice image clearly shows the well thickness to be 2–3 monolayers, confirming that the growth rate obtained from thick layers is accurate for very short growth times. These results demonstrate that atmospheric pressure organometallic vapor‐phase epitaxy can produce extremely thin GaInAs/InP quantum wells of a few monolayers.

ISSN:0021-8979    

DOI:10.1063/1.345193

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The reaction between copper and silicon is studied using differently oriented Si and Cu. Copper films, deposited by electron‐beam evaporation at room temperature without intentional heating of the substrates, show an epitaxial relation with the Si substrates, resulting in (100)‐ and (111)‐oriented Cu films on the (100) and (111) Si, respectively. An orientation dependence is observed for the Cu‐Si reaction, with different phases of the silicides formed. At 200 °C, for example, the silicide formation rate is about five times faster for the (100)‐oriented structures than for the (111) ones. An interface bonding model is used to relate to the orientation dependence observed, and is compared with previous work on the Au‐Si and Au‐Cu systems. The diamond structure of Si favors the (100) surface for reaction, as is observed for the Au‐Si reaction. The face‐centered‐cubic structure of Cu, however, favors the (111) orientation for reaction. The latter is observed for the Au‐Cu reaction using epitaxial Cu films on Si. Combined bonding consideration for both Cu and Si indicates a dominant role of Si release at these temperatures.

ISSN:0021-8979    

DOI:10.1063/1.345194

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Fe2O3film (∼110 A˚) on crystalline Al2O3substrate is treated by ruby laser pulses at different energy densities up to a maximum of ∼7.5 J/cm2, and the transformations are examined by conversion electron Mo¨ssbauer spectroscopy and small‐angle x‐ray diffraction measurements. It is observed that transformations begin to appear in the sample at an energy density of ∼3.0 J/cm2although significant modifications are observed only at energy densities higher than about 7.0 J/cm2. The values of hyperfine interaction parameters reveal that the laser treated samples contain FeAlO3and FeAl2O4phases, along with the residual &agr;‐Fe2O3phase. The laser‐mixed state undergoes structural modifications upon thermal annealing, leading to formation of the Fe3O4phase and complete disappearance of the FeAlO3phase.

ISSN:0021-8979    

DOI:10.1063/1.345195

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A method for the quantitative characterization of texture in thin films using x‐ray diffraction is presented. The traditional technique, which makes use of a powder diffractometer, relies on peak intensity measurements at normal incidence. By using pole figure measurements and subsequent orientation distribution analysis we obtain the substantially improved coverage necessary to accurately characterize textures of thin silicon films which exhibit great variation and complexity.

ISSN:0021-8979    

DOI:10.1063/1.345196

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Results one+transmission reemission properties are presented for three single‐crystal W(100) films of thicknesses 1000, 2000, and 3100 A˚ for incidente+energies of 1.4–16 keV. The films were first cleaned with a 10‐s laser pulse, then annealed in O2(10−6Torr), and finally heated in a vacuum (10−9Torr). Thereafter the films showed good reemission properties. The maximum transmitted yields of slowe+were 38% (1000 A˚), 27% (2000 A˚), and 17% (3100 A˚) at incidente+energies of 4, 5.2, and 7.2 keV, respectively. The energy distributions of the reemittede+were characterized by a full width half maximum of 0.15–0.2 eV located at 2.8 eV containing 60%–70% of thee+superimposed onto a nearly uniform distribution covering the energy interval 0–2.8 eV.

ISSN:0021-8979    

DOI:10.1063/1.345197

出版商:AIP    

年代:1990

数据来源: AIP