摘要:

Power spectral density due to deep traps has been calculated in a junction field effect transistor (JFET) by a numerical procedure. Distribution of potential, density of carriers, and occupation factors were evaluated for any point of the structure. Different effects were found depending on the depth of the trap considered, such as spectra different from the pure Lorentzian shape or anomalous behavior of the noise amplitude with reverse voltage applied. The explanation of these effects may be useful for the characterization of midgap levels produced in JFETs under irradiation stress. Good agreement is achieved with the experiment. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115324

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Inversion in conductivity type of GaSb fromp‐ ton‐ has been observed as a result of argon ion beam milling. Electron beam induced current (EBIC) measurements have been employed for detecting the type conversion. Enhancement in the luminescence intensity is seen after ion beam treatment. The type conversion is proposed to occur due to a combined effect of generation of native donors and gettering of native acceptors originally present in the as‐grown samples. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115325

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

&bgr;‐PdAl was studied as a Schottky contact to metalorganic chemical vapor deposition grown In0.52Al0.48As. Intermetallic alloy &bgr;‐PdAl was chosen in order to utilize the Al–In exchange reaction which may occur between PdAl and In0.52Al0.48As, which would result in an enhanced Schottky barrier height.I–V,C–V, and deep level transient spectroscopy (DLTS) were used to determine the contact characteristics. The contact barrier height (&fgr;b) was measured byI–VandC–Vmethods after different annealing conditions, and good agreement betweenI–VandC–Vresults were obtained. The largest &fgr;bvalue is 0.67 eV fromI–Vmeasurement (0.69 eV fromC–V) after the diode was annealed at 450 °C for 1 min. DLTS measurements were carried out to examine the effect of deep traps in the In0.52Al0.48As layer. Two deep levels were found, but the concentrations are lower than the intrinsic donor concentration obtained from the Hall method. The activation energies for these two deep levels obtained from an Arrhenius plot are 0.38 and 0.65 eV, respectively. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115326

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Surface roughening of (100) Si at low temperatures during electron cyclotron resonance hydrogen plasma cleaning is studied in an ultrahigh vacuum environment. The effects of process parameters on surface roughness are quantitatively analyzed by atomic force microscopy besides reflection high energy electron diffraction. Crystalline defect morphology is studied by transmission electron microscopy to understand its role in surface roughness. Surface roughness is strongly related to the nucleation and growth of {111} platelet defects at the Si subsurface region and the preferential etching at positions where {111} platelet defects intersect the Si surface. Hydrogen ion flux and substrate temperature can be successfully controlled to tailor the {111} platelet defects, therefore, surface roughness. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115327

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Using deep level transient spectroscopy (DLTS) theXconduction‐subband energy levels in an AlAs well sandwiched by double GaAs layers were determined. Calculation gives eight subbands in the well with well width of 50 A˚. Among them, five levels and the other three remainders are determined by using the large longitudinal electron effective massm1(1.1m0) and transverse electron effective massmt(0.19m0) atXvalley, respectively. Two subbands with the height energies were hardly detectable and the other six ones with lower energies are active in the present DLTS study. Because these six subbands are close to each other, we divided them into three groups. Experimentally, we observed three signals induced from the three groups. A good agreement between the calculation and experiment was obtained. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115328

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Characteristics of Schottky barriers formed on homoepitaxial diamond film have been studied. Current–voltage characteristics of Al contacts on both the as‐grown film and the oxidized film show rectification. On the other hand, ohmic property is observed on Au/as‐grown film while Au/oxidized film shows rectification. These results imply that the mechanism of the barrier formation on the as‐grown diamond is drastically changed by oxidation. The difference of electrical properties between the as‐grown film and the oxidized film is also observed from capacitance–voltage characteristics. This result suggests that additional acceptors which are not related to boron, exist in the as‐grown film and disappear after oxidation. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115329

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A comparison of the photoluminescence of Er‐doped hydrogenated amorphous silicon and crystalline silicona‐Si:H(Er) andc‐Si(Er), is presented. It is shown thata‐Si:H(Er) exhibits efficient room‐temperature photoluminescence at 1.537 &mgr;m which is as strong as the emission from optimizedc‐Si(Er) at 2 K. Most remarkably, there is practically no temperature quenching of the emission intensity in the range 2–300 K. The experiments suggest that the lifetime connected with the Er‐induced emission is considerably shorter ina‐Si:H(Er) than inc‐Si(Er) which may be responsible for the different dependences of the photoluminescence intensity on the temperature, chopping frequency, and excitation power. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115330

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Influence of the surface on the radiative recombination is studied in near‐surface (NS) strained Si1−xGex/Si quantum wells (QWs). The luminescence intensity of NSQWs is clearly diminished as the Si cap thickness decreases due to carrier capture to the surface. However, the luminescence diminution discloses a saturable behavior with increasing excitation density. Time‐resolved measurements reveal selective electron capture to surface traps as being the controlling process in the luminescence attenuation, and there is no signature of quantum mechanical hole tunneling to the surface. Results of potential‐biased luminescence lend further support to the electron‐controlled picture of the luminescence attenuation in Si‐based near‐surface geometry. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115331

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have grown Al‐free reliable 877 nm In0.49Ga0.51P/GaAs light‐emitting diodes (LEDs) on Si substrates by metalorganic chemical vapor deposition. The conventional Al‐containing Al0.3Ga0.7As/GaAs LEDs on Si substrates exhibit rapid degradations because of the formation of dark‐line defects (DLDs). On the contrary, the In0.49Ga0.51P layer on the GaAs/Si substrate exhibited a 300 K electron mobility of 950 cm2/V s with the carrier concentration of 3.8×1017 cm−3, no residual stress and a lower surface recombination velocity. The In0.49Ga0.51P/GaAs LED on Si shows the stable operation for more than 2000 h, which results from the suppression of the formation of DLDs. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115332

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report novel current–voltage characteristics in an InP‐based resonant‐tunneling high electron mobility transistor (RTHEMT). This device incorporates a pseudomorphic InGaAs/AlAs/InAs resonant‐tunneling diode into the source of a nonalloyed ohmic contact InAlAs/InGaAs high electron mobility transistor. Both pronounced negative differential resistance and negative transconductance are observed at room temperature. Most significantly, a near‐flat valley current is obtained in the output current–voltage characteristics. This feature is achieved by the nonalloyed ohmic contact cap layer structure employed in the HEMT, which significantly reduces the parasitic resistance. The novel characteristics of RTHEMTs should lead to many attractive circuit applications. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115333

出版商:AIP    

年代:1995

数据来源: AIP