摘要:

The three‐dimensional treatment of heat flow in the photoacoustic effect is extended to allow for thermal conduction to the cell walls. The typical effect is to reduce the photoacoustic signal when thermal waves extend to the cell wall with appreciable amplitude, although small increases may also occur. Results are in good agreement with recent experimental data. Comparisons with predictions from one‐dimensional models are given.

ISSN:0021-8979    

DOI:10.1063/1.328505

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A four‐phase complex refractive index‐model approximation coupled with multiple‐angle‐of‐incidence ellipsometric measurements is utilized in an analysis of ion‐implantation damage in silicon. The four phases refer to the ambient, native oxide, implant layer, and substrate. The analysis is applied to phosphorus implants as functions of various ion‐dose ranging from 5×1012to 1×1016ions cm−2, and effective energies from 36 to 120 KeV, for both monomer (P+) and dimer (P+2) species. Implant depths are found to be related to the implant parameters and are found to be equal toRP+1.08 &Dgr;RPwhereRPis the projected range and &Dgr;RPis the projected standard deviation of the implanted ion. This relationship is invariant with respect to effective energy, ion dose, and species. Changes in refractive index, extinction coefficient, and reflectivity are readily detected at doses as low as ∼1013ions cm−2. A decrease in extinction coefficient at high doses suggests that ion‐beam annealing is occurring. In general, changes in optical constants reflecting implant damage are larger for the dimer than the monomer, increase with ion dose, and decrease as the effective energy decreases.

ISSN:0021-8979    

DOI:10.1063/1.328506

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The theory of free‐carrier absorption in nondegenerate semiconductors in the presence of quantizing magnetic fields is used to calculate the absorption of electromagnetic radiation polarized perpendicular to the magnetic field direction. We find that using the Born approximation, the absorption coefficient diverges logarithmically for radiation polarized transverse to the magnetic field whenever the photon frequency is an integral multiple of the carrier cyclotron frequency, i.e., when &OHgr;=n&ohgr;c. The magnetic field dependence of the absorption for the transverse configuration, like that for the longitudinal configuration, can be explained in terms of phonon‐assisted transitions between the various Landau levels of the carriers.

ISSN:0021-8979    

DOI:10.1063/1.328507

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A low‐temperature photoluminescence study of bulk polycrystalline InP is presented. The dominant acceptor feature common to all samples at 6 K is a pair band at 1.382 and 1.387 eV, possibly associated with carbon impurity. The temperature dependence of intensity, linewidth, and spectral position of a vacancy‐impurity band at 1.078 eV is reported for the first time and compared with predictions of the configuration‐coordinate model. In addition, an unusual band at 1.209 eV which is formed over long periods of time at temperatures below 30 K is described.

ISSN:0021-8979    

DOI:10.1063/1.328462

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

When crystalline InP is subjected to mechanical damage by scratching or cleaving in vacuum, a new luminescence transition near 1.3 eV results. The spectrum consists of a doublet split by ∼5 meV. Thermal quenching occurs above 100 K with an activation energy of 120 meV. Annealing to 300 K in the dark removes the luminescence centers, and the annealing temperature is reduced to about 200 K with illumination. We interpret the luminescence centers as native defects acting as electron traps of depth ∼100 meV. The defects are believed to be introduced by the process of plastic deformation of the crystal.

ISSN:0021-8979    

DOI:10.1063/1.328463

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

General theoretical expressions appropriate to calculating the internal and external quantum efficiency of photoluminescence (PL) are derived for a semiconductor of thicknessdand bounded by two surfaces with different surface‐recombination velocities. The external efficiency expected from thin and thick layers is compared and contrasted. Under certain conditions and adopting reasonable assumptions, we indicate how a single measurement of the steady‐state PL can yield information about the minority‐carrier diffusion length.

ISSN:0021-8979    

DOI:10.1063/1.328464

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Results of photoluminescence and Hall effect measurements ofp‐type Ge‐doped Ga0.60Al0.40As grown by liquid phase epitaxy are reported. The effective segregation coefficient for Ge for growth at 785 °C is estimated to be ∼2×10−3. The photoluminescence spectra at 5.5 K are characterized by two edge emission bands at ∼1.91 and ∼1.88 eV and a broadband at ∼1.55 eV. The edge emission bands are identified to be donor‐acceptor pair recombination bands involving the same donor but two different acceptors. The ionization energy of the donor is estimated to be 50–60 meV and the acceptor ionization energies are estimated to be ∼60 and ∼100 meV for the 1.91‐ and 1.88‐eV bands, respectively. The deep acceptor is believed to involve a background impurity, most likely C or Si. It is suggested that the 1.55‐eV band arises from a next‐nearest neighbor complex consisting of Ge on an arsenic site and an As vacancy. Post‐growth annealing treatment at 830 °C is found to decrease the photoluminescence intensity suggesting the presence of annealing induced nonradiative centers.

ISSN:0021-8979    

DOI:10.1063/1.328465

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The use of spectrally and spatially revolved photoluminescence for investigation of GaAs0.6P0.4light‐emitting diodes is described. A HeCd laser focused to 8 &mgr;m was used for excitation. Photoluminescence spectra were taken at 95 and 300 K. They show distinct differences between thep‐type junction area and then‐type substrate region. Devices with a different electroluminescence efficiency showed corresponding differences in their photoluminescence behavior. Thep‐njunction depth was found to be a critical parameter, influencing electroluminescence as well as the photoluminescence spectra. Spectrally resolved photoluminescence can be used as a tool to characterize light‐emitting diode materials and devices at different production stages.

ISSN:0021-8979    

DOI:10.1063/1.329799

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

CdS layers on glass substrates show different colors from deep to light yellow depending on the evaporation conditions. We found that the shorter the absorption edge wavelength, the higher the carrier density in the layer. The correlation shows typical features of the Burstein‐Moss shift well known from narrow‐gap III‐V compound semiconductors.

ISSN:0021-8979    

DOI:10.1063/1.329800

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Electrochemical adsorption of Ag and Cu ona−Se1−xGexfilms has been studied as a function of the composition of the films, angle of deposition (obliqueness), film thickness, pre‐illumination of the films and temperature of the electrolytic solution. Metal adsorption is due to th eoxidation of germanium atoms by the metal ions present in the electrolyte. Its enhancement with obliwueness (angle of deposition f the film) arises due to increased surface defect sites/dangling bonds associated with the Ge atoms. Adsoprtion decreases for pre‐illuminateda−Se1−xGexfilms, presumably as a result of changes in the surface topography arising from structural rearrangements of the defect centers.

ISSN:0021-8979    

DOI:10.1063/1.329801

出版商:AIP    

年代:1981

数据来源: AIP