摘要:

A new thermally stable, low‐resistance In‐based ohmic contact ton‐type GaAs has been developed. The contacts consist of ion‐beam sputtered Ni (5 nm)/In (5 nm)/Ni (5 nm) layers with a magnetron sputtered WNxoverlayer. A low‐contact resistance of ∼0.3 &OHgr; mm was obtained by rapid thermal annealing at 750 °C for ∼5 s. The contact resistance and the excellent contact morphology remained unchanged after annealing at 400 °C for more than 100 h. The present deposition technique provides several advantages over previously reported electron‐beam evaporated In‐based contacts. In particular, the ability to deposit a thick WNxoverlayer simplifies GaAs integrated circuit (IC) fabrication by (a) eliminating the need for separate diffusion barrier deposition and patterning steps, and (b) providing for low‐sheet resistance (∼2 &OHgr;/&laplac;) IC interconnect capabilities. In addition, sputter deposition allows for the controlled incorporation ofn‐type dopants into the metallization if further reduction of the contact resistance is required.

ISSN:0003-6951    

DOI:10.1063/1.106031

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

This letter presents a detailed study of the temperature dependence of submicron pseudomorphic InGaAs on GaAs substrate modulation doped field‐effect transistors (MODFETs), doped‐channel metal insulator field effect transistors (MISFETs), and metal semiconductor field‐effect transistors (MESFETs). We determine similar variation in the measured extrinsic current gain cutoff frequency,FT, and similar dependencies of the effective electron velocity,veff, with reduced lattice temperature for the different field‐effect transistors. Theveff∼T−bwhere 0.15<b<0.20 over the temperature range of 300 to 110 K. These results provide direct experimental evidence that the saturated velocity of electrons is the most important parameter for high‐speed operation and with proper design these different pseudomorphic InGaAs/GaAs field‐effect transistors provide similar potential for high‐speed operation.  

ISSN:0003-6951    

DOI:10.1063/1.106032

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Systematic studies have been made for the first time on the basic properties of AlxGa1−xAs (x=0.2–0.7) grown by molecular beam epitaxy in the wide growth temperature range of 540–780 °C with As4and As2. Theforbiddengrowth temperature region (FTR), where the specular smooth surface cannot be obtained, has been found to depend strongly upon both the As species and the AlAs mole fractionx. FTR does not change withxin the case of As4; however, in the case of As2, FTR does not exist forx=0.2 and it increases withxfrom 0.3–0.7. Photoluminescence ofn‐Al0.3Ga0.7As (Si=1×1018cm−3) grown with As2shows lower intensity and higher sensitivity to growth temperature than those of samples grown with As4. Deep level transient spectroscopy has been measured onn‐Al0.7Ga0.3As (Si=2×1016cm−3). New electron traps are found in layers grown with As2.

ISSN:0003-6951    

DOI:10.1063/1.106033

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report a novel technique for growing GaAs on Si substrates with a low density of threading dislocations. The process involves patterning a 200 nm period sawtooth grating on (100) Si using a combination of holographic lithography and wet chemical etching. The GaAs layers grown by metalorganic chemical vapor deposition on such substrates exhibit a dramatic reduction in the density of threading misfit dislocations, even when the grown layers are thin. Twins and stacking faults are also reduced dramatically by eitherinsituthermal‐cycle growth orexsiturapid thermal annealing.

ISSN:0003-6951    

DOI:10.1063/1.106034

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A new capacitance method was developed to investigate properties of the SiNX:H/c‐Si interface. By comparison of the frequency dependence ofC‐Vcharacteristics ofp‐ andn‐typec‐Si substrate sample pairs, flatband voltage for an intrinsic substrate sample can be determined. Analyses of two kinds of frequency dependence, i.e., the variation of voltage at flatband capacitance and the variation of capacitance at flatband voltage, disclose different aspects of the interface state density with respect to the energy level in the band gap, response time, and ionized state. Donor states are predominant in the investigated interface.

ISSN:0003-6951    

DOI:10.1063/1.106035

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have annealed Si‐SiO2structures at an elevated temperature in He(g) with SiO(g) added to the ambient. A SiO2decomposition reaction that normally forms large voids in a thin SiO2film during annealing in He(g) is not detected with the added SiO(g). Instead, chemically reactive SiC impurity sites which initiate the SiO2decomposition reaction are found segregated along crystallographic planes in the substrate at the Si‐SiO2interface. The mechanism and technological importance of this interfacial reaction are discussed.

ISSN:0003-6951    

DOI:10.1063/1.106036

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Thep‐type nature of unintentionally doped GaSb molecular beam epitaxy grown layers has been attributed to native defects resulting from insufficient Sb incorporation. As a means to improve the quality of GaSb epilayers, growth on (311) Bsubstrates was studied and shown to produce Te‐doped GaSb layers with room‐temperature mobilities of 6780 cm2/V s at carrier densities of 9×1015cm−3and AlGaSb/GaSbp‐i‐ndiode structures with breakdown voltages as high as 20 V. These mobilities and breakdown voltages are the highest achieved for molecular beam epitaxy grown GaSb‐based structures.

ISSN:0003-6951    

DOI:10.1063/1.106037

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The electron‐electron scattering time &tgr;eefor a hot electron with excess energy &Dgr; above the Fermi surface of a two‐dimensional (2D) electron gas is calculated as a function of temperature, carrier density, and excess energy &Dgr; for a typical heterostructure. &tgr;eeincreases with decreasing temperature and saturates for temperatures belowkT<&Dgr;. The electron‐electron scattering lengthleelimits the size of electron quantum interference devices. We show that electron‐electron scattering lengthsleearound 1 mm should be possible at temperaturesTbelow 1 K and electron energies &Dgr; below 0.1 meV.

ISSN:0003-6951    

DOI:10.1063/1.106039

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We consider the effects on photocurrent spectra of the finite transit times of carriers through the 2‐&mgr;m‐thick intrinsic region of ap‐i‐ndiode containing multiple quantum wells. If the transit time is comparable to or greater than the carrier recombination time, the photocurrent spectra show severe distortion. We have observed an anomalously large decrease in the diode’s quantum efficiency, accompanied by a compression of the spectral features and eventually an apparent splitting of each photocurrent peak into two separate peaks, as the electric field is lowered. A carrier‐transport model is presented that accurately describes the essential experimental features.

ISSN:0003-6951    

DOI:10.1063/1.106012

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have investigated the influence of hydrostatic pressure on the tunneling processes between two independently contacted two‐dimensional electron gas systems which are separated by a doped AlGaAs barrier. For magnetotunneling data, the pressure dependence of the GaAs effective massm* was determined betweenp=0 and 10 kbar. In this range, we find a linear pressure dependence ofd(m*/me)/dp=8×10−4kbar−1for the electrons in the two‐dimensional channels. At higher pressures several new resonances are observed, which correspond to transition energies in the order of 4 meV. These effects are most probably explained by local phonon modes related to theDXcenters inside the barrier.

ISSN:0003-6951    

DOI:10.1063/1.106013

出版商:AIP    

年代:1991

数据来源: AIP