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The Raman scattering by longitudinal‐optical (LO) phonon‐plasmon‐coupled (LOPC) mode in carbon‐doped p‐type InGaAs with indium composition x≊0.3 and hole concentration from 1017 to 1019 cm−3 grown by metalorganic molecular beam epitaxy was studied experimentally. Only one LOPC mode appears between the GaAs‐like and InAs‐like LO modes was observed. The peak position of the LOPC mode is near the GaAs‐like transverse‐optical mode frequency and is insensitive to the hole concentration. The linewidth and intensity of the LOPC mode are dependent strongly on the carrier concentration, while the two LO modes decrease and become invisible under the high doping level. It was shown that the plasmon damping effect plays a dominant role in Raman scattering by LOPC mode for the p‐type InGaAs.

Gas source molecular‐beam epitaxy (MBE) has been studied as a low‐temperature Si and SiGe epitaxial method. Specular single‐crystalline silicon films were successfully grown by the gas source Si MBE technique at a substrate temperature of about 650 °C. N‐type doping was carried out using PH3 gas as a dopant and the maximum electron concentration of 2.9x1019cm−3 was obtained. Furthermore, p‐type doping using B2H6 gas was carried out for the first time and the maximum hole concentration of 9.5×1017cm−3 was successfully achieved. The SiGe alloy layer was also grown by the gas source MBE technique using GeH4 as a Ge source gas. The Ge concentration of the sample could be precisely controlled by the molar fraction of Ge in supply and it was increased up to 0.30 with increasing the gas ratio of GeH4 to Si2H6.

Using double crystal x‐ray diffractometry (XRD) and transmission electron microscopy (TEM), the annealing effects on heavily carbon‐doped GaAs films were studied. From isochronal annealing, the evolution of compressive strain in carbon‐doped GaAs films was observed by XRD. From cross‐sectional TEM, unusual misfit dislocations with extra‐half planes on the GaAs side were observed in the sample annealed at 900 °C for 30 min in addition to normal misfit dislocations with extra‐half planes on the film side. A possible mechanism for the formation of such misfit dislocations is proposed based on the over‐relaxation of misfit strain in the film.

Electroluminescence (EL) and photoluminescence have been measured from thin film structures of heavily carbon‐doped GaAs on crystalline semi‐insulating GaAs substrates. EL is only detected when the p‐type film is biased positively. From this and the spectral distribution, it is concluded that there are heterojunction interface states at about 50 meV below the conduction band, with a concentration roughly estimated as 1017 cm−3.

Two novel carbon‐doped structures grown by metalorganic molecular beam epitaxy were used to study thermal stability over the temperature range from 650 to 800 °C. Each structure consists of several GaAs layers with different carbon concentrations to characterize thermal stability of GaAs layers with various carbon concentrations simultaneously. The structure shows no significant carbon diffusion even after an 800 °C‐240 min anneal. However, the hole concentration of each carbon‐doped GaAs layer in both structures has decreased, and a decrease of the hole concentration is more significant for a higher carbon concentration. With increasing the annealing time or temperature, the hole concentrations of all carbon‐doped GaAs layers approach to the same value, low 1019 cm−3.

Ga2Se3 films have been grown by molecular beam epitaxy. Single‐crystal Ga2Se3 films were obtained for the first time on (001) GaP substrates at a substrate temperature of 550 °C and at a VI/III flux ratio greater than 15. Extra diffraction spots with weak intensity were observed in reflection high‐energy electron diffraction patterns of the Ga2Se3 films grown at a VI/III ratio above 150. These extra spots were also observed in the transmission electron diffraction pattern. The extra points are attributed to the ordering of native Ga vacancies in the defect zinc blende structure.

Series resistance of Zn‐doped p‐ (GaAl)As/p‐GaAs/n‐GaAs solar cells fabricated by liquid‐phase epitaxy has been theoretically calculated as a function of sheet resistance of p‐ (GaAl)As and p‐GaAs, and also measured experimentally. The series resistance is strongly affected by the p‐layer sheet resistance. From the resistivity measurement, it was found that the resistivity of Zn‐doped p‐Ga0.3Al0.7As is about 10 times higher than that of the Zn‐diffused p‐GaAs layer. The high resistivity of Zn‐doped p‐Ga0.3Al0.7As is caused by the deeper acceptor level (Ea=90 meV) than that for Zn‐doped p‐GaAs (Ea=20 meV). Fabricated p‐p‐n solar cells have been operated under a concentration of 700 suns. The cells showed nearly constant efficiency at a concentration lower than 100 suns, but the efficiency decreased monotonically above 500 suns because of the series resistance effect. The additional Zn diffusion into p‐ (GaAl)As has also been performed after the LPE growth in a closed tube by using ZnAs2. The reduction of p...

ZnSe and ZnTe thin films and ZnSe‐ZnTe strained‐layer superlattices (SLS) have been successfully grown by atomic layer epitaxy (ALE) using molecular‐beam epitaxy. The ALE growth of ZnSe and ZnTe was achieved at substrate temperatures between 250 and 350 °C and between 240 and 280 °C, respectively. The Zn, Se, and Te beam intensities necessary to achieve ALE growth were evaluated. Under optimum growth conditions, the surfaces of ZnSe and ZnTe thin films were very specular without any surface structure. Modulation‐doped n‐type SLSs have been prepared by ALE using Cl as a n‐type dopant. The carrier concentration of superlattices grown by ALE (3.8×1016 cm−3) was three orders of magnitude higher than those of superlattices grown by conventional molecular‐beam epitaxy.

The optical and electrical properties of hydrogenated amorphous silicon films produced by rf glow discharge decomposition of disilane diluted in helium (Si2H6/He=1/9) have been studied while systematically varying the film deposition rate. The properties and composition of the films were monitored by measuring the optical band gap, IR vibrational spectrum, dark conductivity, and the photoconductivity as a function of the deposition rate. The photoluminescence of the high deposition rate films gave a peak at 1.33 eV. These films, whose properties are rather similar to those of the conventional a‐Si:H films prepared from monosilane, have been used to fabricate nip‐type a‐Si:H solar cells. At a deposition rate of 11 A/sec, a conversion efficiency of 6.86% was obtained. This high efficiency shows that disilane is applicable for mass production fabrication of a‐Si:H solar cells.

ZnTe–CdS heterojunction LED, which was prepared on the ZnTe substrate by CdS vapor growth, showed the red light emission at 300°K. The EL spectra had a peak at 1.78–1.80 eV at 300°K, and two peaks at about 2.10 and 1.55 eV at 77°K. The existence of the ZnxCd1−xTe mixed crystal with a graded band structure at the heterojunction interface was shown from the results of the photovoltage spectra and transmittance analysis of the heterojunction. The formation of the mixed crystal was found to be due to Cd diffusion into the ZnTe substrate during the epitaxial growth. From photoluminescence measurements, it is concluded that the red emission of ZnTe–CdS LED may originate from the ZnxCd1−xTe mixed crystal layer. Thus, efficient red emission could be obtained in our ZnTe–CdS heterojunctions on account of the mixed crystal layer, which reduced high‐energy barriers for electrons and holes.

The metalorganic molecular‐beam epitaxial growth of ZnSe and ZnS on (100) GaAs has been demonstrated and characterized. Diethylzinc and diethylselenide were used for the ZnSe growth, while for the ZnS growth both hydrogen sulfide and diethylsulfide (DES) were tested as sulfur sources. The dependence of the growth rate on various growth conditions was investigated to clarify the growth mechanism. When group VI alkyls were used as sources, pyrolysis in a cracking cell was required, unlike metalorganic chemical vapor deposition. Interesting differences in growth kinetics and in crystallinity between H2S‐based and DES‐based ZnS have been found. Photoluminescence spectra of ZnSe layers measured at 4.2 K showed resolved exciton emissions. However, donor‐acceptor pair emission lines attributed to a Li acceptor (LiZn) were also observed. Smooth, monocrystalline ZnS layers could be grown at substrate temperatures above 250 °C by using cracked H2S and DES, and above 150 °C by using uncracked H2S. Photoluminescence ...

n‐Ga1−xAlxAs/p‐GaAs/n‐GaAs heterojunction transistors with high Al concentrations have been fabricated by the conventional liquid‐phase epitaxial method. Electrical measurements showed that the transistors have a common emitter current gain of up to 1600. The current gain varies with the emitter injection level because of the defect‐current component, which is the recombination current in the depletion region. It has been made clear, however, that the effect of the defect current was reduced in transistors grown at low temperature (∼750 °C). The variation of the electron diffusion length Ln with the device operating temperature has been calculated by using the current gain at each temperature. Furthermore, the phototransistor characteristics have been widely investigated.

Molecular‐beam epitaxy (MBE) with ion beams as dopants is proposed, and experiments with Zn ions in GaAs and AlxGa1−xAs are reported. In conventional MBE, impurities with low sticking coefficients have not been used because doping into MBE layers involves simultaneous evaporation. In this paper, a method of ionizing the dopant molecular beam and increasing its effective sticking coefficient is proposed. By means of ionization, an effective sticking coefficient of ∼0.03 for Zn ions in GaAs and AlxGa1−xAs is obtained as compared with a value of ∼10−7 for neutral Zn. This value does not vary even with the mole fraction of AlAs in the system AlxGa1−xAs. A strong ion acceleration is not essential for increasing the sticking coefficient, and ionized dopants arriving at the substrate even without enough kinetic energy for penetration beneath the surface react and bond with the surface atoms sufficiently to prevent reevaporation. Crystallographic characteristics of ion‐doped GaAs and AlxGa1−xAs films are as good ...

The theoretical spectral response of the graded‐band‐gap pGa1−xAlxAs‐nGaAs solar cell is calculated by solving the continuity equations. The electric fields produce a collection efficiency two times larger than that of the abrupt heterojunction diodes at wavelengths less than 700 nm for surface recombination velocities of 106–107 cm/sec. The graded‐band‐gap diode can be operated at high frequencies because of the reduced transit time of minority carriers in the p‐type layer. A graded‐band‐gap pGa1−xAlxAs‐nGaAs solar cell is fabricated by utilizing the diffusion of Al in the Ga melt. The gradient of the energy gap is evaluated by photoresponse and photoluminescence measurements. The photoluminescence shows a broad emission peak from 700 to 800 nm at 77 K.

ZnSe thin films were grown on (100) and (111) oriented Si substrates by molecular beam epitaxy. The single‐crystalline ZnSe films were obtained in the substrate temperature range of 300–450 °C. The epitaxial layers were evaluated by reflection high‐energy electron diffraction, x‐ray diffraction, etch pit density, photoluminescence, and Hall effect measurements. Etch pit density was estimated to be 3×105 cm−2. The carrier concentration and electron mobility of the epitaxial ZnSe layers at room temperature are 1.3×1017–2.8×1017 cm−3 and 170–250 cm2/V s, respectively. These epitaxial films were applied to Au/ZnSe:Mn/Si dc‐operated electroluminescent cells. The maximum quantum efficiency of 2.2×10−2 (30.4 V, 6.3×10−5 A/cm2) was achieved.

ZnSe thin films were grown by plasma‐assisted metalorganic chemical vapor deposition (MOCVD). Plasma‐assisted MOCVD is a technique combining rf glow discharge decomposition (at 13.56 MHz) with conventional metalorganic chemical vapor deposition. This process may offer several advantages such as low‐temperature growth, high chemical reactivity, cleaning effect of substrate surface, and good surface morphology. The metalorganic sources used were diethylzinc and diethylselenide. The epitaxial films were obtained at the low substrate temperature of 250 °C by plasma‐assisted MOCVD. The grown films showed excellent surface morphology and uniformity over a large area. These films were applied to Al/ZnSe:Mn/ITO (indium tin oxide) dc‐operated electroluminescent cells. As a manganese source, di‐π‐cyclopentadienyl manganese [(C5H5)2Mn] was successfully used.

Electrical properties and the acceptor energy level in Zn‐doped p‐Ga1−xAlxAs (0

Optical properties of ZnSe–ZnTe strained‐layer superlattice (SLS) grown on InP substrates were evaluated by photoluminescence. The luminescence peak intensity and position were affected by the photoexcitation intensity. The line shape was also affected by the growth temperature. The peak position was shifted by tailoring the structure of the superlattice, but it did not correlate exactly with previously reported theoretical values. We have reconsidered their data, and a better result on theoretical calulation was achieved. The luminescence color changed in the visible region from green to red. This SLS could be a new material for optoelectronic devices.

Two types of ZnSe:Mn dc thin‐film electroluminescent (EL) devices were prepared by molecular beam growth: a Au/ZnSe:Mn/GaAs cell with a single‐crystal ZnSe:Mn host layer and an Al/ZnSe:Mn/ITO cell with a polycrystal ZnSe:Mn host layer. Modulation doping was used to investigate the active region in the ZnSe:Mn layer. It was found that threshold voltage characteristics of the Au/ZnSe:Mn/GaAs cell were influenced by the Mn doping position in the ZnSe host layer, but in the Al/ZnSe:Mn/ITO cell, there was no dependence of threshold voltage on the Mn doping position. The dependence of luminescence intensity‐injection current characteristics on the Mn doping position showed that the excitation probability of Mn luminescence centers by injected electrons increased in the region close to the negative electrode for both types of EL cells.

The two‐band transport model is expanded in order to analyze the Hall mobility of p‐type III–V compound semiconductors. Using this model, the drift and the Hall mobilities can be calculated separately. The alloy scattering as an additional scattering mechanism in alloy semiconductor systems is assumed and the Hall mobility of p‐type Ga1−xAlxAs is analyzed. By comparing the theoretically calculated Hall mobility with the reported Hall mobility data of high purity p‐GaAs, the acoustic phonon deformation potential and the optical phonon deformation potential were found to be 7.0 and 11.5 eV, respectively. Theoretical calculations showed that the acoustic and nonpolar optical phonon scattering are more prominent than the polar optical phonon scattering at 300 K in the entire Al compositional range. The alloy scattering potential was determined comparing the theoretically calculated values with the Hall mobility of liquid phase epitaxial p‐type Ga1−xAlxAs. Best agreement in the compositional variation at room ...

Lattice strain and lattice dynamics of ZnSe‐ZnTe strained‐layer superlattices (SLSs) were examined by means of transmission electron microscopy and Raman scattering. Superlattice structures were confirmed from both transmission electron diffraction patterns and bright field images of the samples. Lattice distortions which originated from misfit strains were observed by the lattice image mode. The crystallinity of the adjacent layers was degraded when the layer thickness became large and polycrystalline structures were observed when the layer thickness exceeded the critical layer thickness. Raman scattering was used to assess the magnitude of the strain in the SLSs. Optical phonon frequencies of the components in SLSs were different from those frequencies of the bulk materials. The frequency shifts were used to quantify the strains in the SLSs. The observed shifts corresponded to the calculated values.

The carrier continuity equations for both holes and electrons have been solved in amorphous Si (a‐Si) p‐i‐n solar cells, including the diffusion term, hole‐electron recombination term represented by a Shockley–Read model, and the interface recombination effect. Furthermore, the characteristics illuminated through the p and n layers have been calculated and compared. It is shown that when the i layer is intrinsic, the fill factors obtained by illuminating through the p and n layer are almost the same and both are more than 0.6. Furthermore, we found that the fill factor strongly depends on the interface recombination and a fill factor of more than 0.7 can be obtained by using heterojunction such as a‐SiC:H/a‐Si:H to decrease the interface recombination effect.

A detailed study has been made of interdiffusion in ZnSe‐ZnTe strained‐layer superlattices (SLSs) grown by molecular‐beam epitaxy (MBE) at a growth temperature of 320 °C. In x‐ray diffraction measurements, the satellite peak intensities relative to the zero‐order peak intensity decreased with annealing time. The interdiffusion coefficient D was calculated assuming a linear diffusion model. The values of D=3.6×10−21 to 2.2×10−19 cm2/s at an annealing temperature of 500 °C were obtained for the ZnSe‐ZnTe SLSs. In the high‐resolution transmission electron microscopy (HRTEM) image of as‐grown SLSs, the presence of fine superlattice structures was seen, but for interdiffused samples stripes due to the periodic superlattice structures were not visible and many dislocation lines were observed. These results suggest that the structure of SLSs is significantly modulated by thermal annealing at a temperature higher than the growth temperature.

The diffusion of beryllium and zinc into GaAs substrates during liquid phase epitaxial growth of p‐Ga0.2Al0.8As layers was investigated. The diffusion coefficients were determined from the profile of free‐carrier concentration in the p‐GaAs region. Comparing the diffusion coefficients of Be and Zn, the diffusion coefficient of Be was found to be about ten times higher than that of Zn in the temperature range above 750 °C. For Be diffusion, if the surface free‐carrier concentration in the p‐GaAs layer is lower than about 6×1018 cm−3, the diffusion can be expressed as diffusion from a semi‐infinite source and the free‐carrier concentration profiles are represented by the error function complements. With regard to temperature dependence, the diffusion coefficient takes the form D=D0 exp(−E0/kT), where D0=0.66 cm2 s−1 and E0=2.43 eV in the temperature range 700–900 °C. If the surface free‐carrier concentration was higher than about 6×1018 cm−3, anomalous behavior was observed; i.e., the diffusion could be no ...

ZnSe thin films have been grown on (100)‐oriented GaAs and glass substrates by photoenhanced metalorganic chemical vapor deposition from diethylzinc and dimethylselenide with a low‐pressure mercury lamp as a light source. Process temperatures have been varied between 500 and 200° C. Without irradiation of the ultraviolet (UV) light, the growth rate decreases rapidly below 400 °C, whereas with irradiation, the growth occurred in the whole temperature range investigated, and the enhancement of the growth rate was observed above 400 °C. Furthermore, the enhancement of the preferential orientation of ZnSe films grown on glass substrates by the UV irradiation was also observed.

p‐type GaAs with doping levels of up to 5.8×1020 cm−3 has been grown by metalorganic molecular‐beam epitaxy (MOMBE) using carbon (C) as a dopant. The mobility and minority‐carrier diffusion length of the C‐doped MOMBE layers were comparable to those of Be‐doped MBE layers. The diffusion coefficient of C at 900 °C was estimated to be 6×10−15 cm2 /s which is about two orders of magnitude less than that of Be (1×10−12 cm2 /s). In addition, the lattice constant of C‐doped GaAs was found to be 5.6533 A which completely matches that of the substrate, while the lattice constant of Be‐doped GaAs decreases to 5.6467 A at a doping level of 2×1020 cm−3 as reported by Lievin et al. [Inst. Phys. Conf. Ser. No. 79, 595 (1985)].

n (GaAl)As‐pGaAs‐nGaAs heterojunction transistors were fabricated by the liquid‐phase epitaxial technique, where two kinds of etchants were used to expose the pGaAs base region. The characteristics of the heterojunction transistors are examined as functions of the injection current density and the temperature. Electrical measurements showed that the transistors have a common emitter current gain β of up to 350. The defect current component in the emitter heterojunction is the recombination current in the depletion region.

Doped hydrogenated amorphous‐microcrystalline mixed‐phase silicon (μc‐Si:H) films were prepared by the mercury photosensitized decomposition of a disilane‐hydrogen gas mixture, by adding phosphine and diborane for n and p type, respectively. The maximum dark conductivity and optical band gap of the films were, respectively, 20 S cm−1 and ∼2.0 eV for n type, and 1 S cm−1 and 2.3 eV for p type. It is most significant that the gaseous ratio of hydrogen to disilane should be enhanced up to 70 for n type, and even 300 for p type, to obtain such a highly conductive and wide gap film. The crystallinity of the photodeposited μc‐Si films appeared to be improved in comparison with that of films by conventional plasma glow discharge technique.

Crystal growth of GaAs using trimethylgallium (TMG) as a Ga source in a molecular beam epitaxial system has been studied. Mirror‐like monocrystalline epitaxial layers of GaAs were easily obtained on a GaAs substrate at the substrate temperature of 530–630°C. Epitaxial layers were p type and the carrier concentration of these films was about 1018–1019 cm−3. In particular, no deposition was observed on a SiO2 film in this TMG‐As4 system. This feature showed the possibility of selective epitaxy of GaAs.

The effects of mercury and krypton on the glow discharge decomposition of disilane have been studied. It is found that mercury‐sensitized plasma decomposition of disilane yields higher deposition rate hydrogenated amorphous silicon (a‐Si:H) films. At a deposition rate as high as 60 A/s no change was observed on the dark and photoconductivities. A similar effect was obtained in krypton‐sensitized plasma decomposition of disilane.

p‐type hydrogenated amorphous silicon (a‐Si:H) films were prepared by the mercury photosensitized decomposition of a disilane‐diborane gas mixture. With increased gaseous impurity ratio (diborane/disilane), the dark conductivity was enhanced. However, the optical band gap was reduced with increasing boron concentration as generally observed in glow discharge produced boron‐doped a‐Si:H films. Wide optical gap (2.0–2.5 eV) hydrogenated amorphous silicon carbide (a‐SiC:H) films were also prepared by the photochemical vapor deposition technique. Acetylene and dimethylsilane were used as the carbon source instead of methane which is usually used in glow discharge system. Moreover, wide optical‐gap, p‐type a‐SiC:H films were photochemically prepared by adding diborane as an impurity to these gas mixtures. A dark conductivity of 3×10−7 (Ω cm)−1 was obtained for p‐type a‐SiC:H films with an optical band‐gap energy of about 2.0 eV.

A novel Si epitaxial growth technique using mercury‐sensitized photochemical vapor deposition has been developed. Epitaxial thin films (300–8000 A) were grown on (100)Si substrates at 100–300 °C from a gas mixture of Si2H6+SiH2F2+H2 by irradiation of a low pressure mercury lamp (1849,2537 A). The growth rate, plotted as a function of the reciprocal substrate temperature, represented an activation energy which was found to be a small value of 0.18 eV. Observation of the surface structure by reflective high‐energy electron diffraction showed fine (100) streak patterns for films grown at 200 °C as well as at 250 and 300 °C.

Hydrogenated amorphous silicon films have been deposited by mercury photosensitized decomposition (photochemical vapor deposition: photo‐CVD) of disilane at a substrate temperature below 300 °C. The structural and optical properties of undoped films are very similar to those of films deposited by rf glow discharge decomposition. The electronic property measurement shows that the conductivity strongly depends on the substrate temperature during deposition. The photoconductivity reaches 5.7×10−3 (Ω cm)−1 (AM1,100 mW/cm2) at a substrate temperature of 200 °C. The dark conductivity is 10−6–10−8 (Ω cm)−1 and the Fermi level is located near the middle of the gap. n‐type doping has been also achieved by adding phosphine as an impurity to disilane. Furthermore, a p‐i‐n a‐Si solar cell was fabricated using photo‐CVD undoped and P‐doped films. The initial cell showed a conversion efficiency of 4.39% under AM1 insolation.

Amorphous Si‐F‐H films were prepared by dc glow discharge in an atmosphere of SiF4 + H2. Optical and electrical measurements have been performed to evaluate the film quality. The photoconductivity of amorphous Si‐F‐H solar cell showed the efficiency of 1.3% under simulated AM1, 100‐mW/cm2 insulation.

An Al/ZnSe:Mn/ITO dc‐operated electroluminescent (EL) cell was prepared by molecular beam deposition. The threshold voltage was 6–10 V, which is the lowest value in these types of EL cells reported so far. The deposited ZnSe:Mn layer was a polycrystal with only (111) orientation and exhibited sharp x‐ray diffraction and reflection high energy electron diffraction patterns which have been hardly obtained by conventional evaporation methods. This low threshold voltage EL cell has a great potential of application in panel displays because of the low cost and the large size of Indium‐Tin‐Oxide (ITO)‐coated glass substrates.

The conduction types of ZnSe‐ZnTe strained‐layer superlattices (SLS’s) have been controlled by using the modulation doping technique. Two kinds of modulation‐doped SLS’s were prepared. One of them consisted of gallium (Ga) doped ZnSe layers and undoped ZnTe layers. The other consisted of undoped ZnSe layers and antimony (Sb) doped ZnTe layers. The conduction types of the samples modulation doped with Ga and Sb were shown to be n and p type, respectively whereas the undoped samples exhibited n‐type conduction. The electrical properties of the undoped and modulation‐doped samples were evaluated by the van der Pauw method. The carrier concentrations of all types of samples were about 5×1013/cm3 at room temperature. The temperature dependence of the electrical properties was measured for an undoped sample and a sample modulation doped with Sb. The carrier concentrations increased with temperature and reached about 1×1017/cm3 at 500 K.

Wide optical band‐gap (2.0–2.3 eV) undoped and boron‐doped hydrogenated amorphous silicon carbide (a‐SiC:H) films have been prepared by both direct photo and rf glow discharge (GD plasma) decomposition of pure methylsilanes or acetylene and disilane gas mixtures. The photochemically prepared p‐type films showed higher dark conductivities and lower activation energies. For an optical band gap of 2.0 eV a high conductivity of 7.0×10−5 (S cm−1) and a low activation energy of 0.33 eV have been measured. The first trial of these wide band‐gap, fairly conductive films as a window layer in a p‐i‐n solar cell showed the high conversion efficiency of 9.46% under AM1 insolation.

A Au/ZnSe:Mn/n‐GaAS dc‐operated electroluminescent cell was prepared by molecular beam epitaxy. The lowest threshold voltage achieved was 3.8 V, and the highest power conversion efficiency and brightness were 7.6×10−5W/W(18 V, 0.0027 A/cm2) and 270 fL(16.8 V, 0.25 A/cm2), respectively. These values are superior to any previously reported in ZnSe:Mn EL cells.

The deposition rate, electronic and optical properties of hydrogenated amorphous silicon films prepared from rf glow discharge decomposition of disilane (Si2H6) diluted in helium have been measured. These films show excellent electrical and optical properties and, most importantly, a high deposition rate coupled with satisfactory solar cell application was realized for the first time. At a deposition rate of 11 A/s, 5.47% and 6.5% conversion efficiencies were obtained with a first trial of n‐i‐p type solar cells deposited on SnO2/ITO glass and metal substrates, respectively.

The spectra of GaAs SH LED’s, which are obtained by LPE growth of Zn‐doped (GaAl)As on Si‐doped n‐type GaAs substrates, are reported. The spectra are shown to be composed of two peaks. The relative peak intensity of the two peaks is found to be dependent on both the temperature and the injection level. The intensity of the low‐energy peak is found to be almost completely eliminated after covering the sides of the diode in order to avoid edge emission. It is concluded that the low‐energy peak is produced by selective absorption of the light traveling in a direction parallel to the junction plane and going out through the edges of the diode. This result is in contradiction with a previous report dealing with the same kind of structure.

Hydrogenated amorphous silicon solar cells were fabricated by photochemical vapor deposition. A three‐separate‐chamber system was newly developed to reduce the contamination of the dopant elements as well as oxygen or water originated by the loading and unloading procedure. Wide optical band‐gap hydrogenated amorphous silicon carbide was prepared using acetylene (C2H2) for the p layer. The deposition conditions for each layer were optimized and the highest‐energy conversion efficiency of 9.64% was obtained. This high conversion efficiency was mainly attributed to the large short‐circuit current which indicated that the quality of the i layer is reasonably good.

The diffusion of beryllium into GaAs during liquid phase epitaxial growth of beryllium‐doped p‐Ga0.2Al0.8As is investigated. The diffusion coefficient D takes the form D=D0 exp(−E0/kT), where D0=11.2 cm2 sec−1 and E0=2.43 eV.

Molecular beam epitaxial growth of GaAs with an ionized Zn beam as dopant is reported. In the normal molecular beam epitaxy, the sticking coefficient of Zn is nearly zero and Zn has not been used as a dopant. By ionizing the Zn atoms, a sticking coefficient of ∼0.03 was obtained, and this value is much larger than that of any other p‐type dopants for GaAs except for Ge which is amphoteric.

Hydrogenated amorphous silicon solar cells were fabricated by photochemical vapor deposition. Wide optical band‐gap (∼2.0 eV) hydrogenated amorphous silicon carbide was employed for the p layer. Acetylene (C2H2) or dimethylsilane (Si(CH3)2H2) was used as a carbon source instead of methane which is usually used in a glow discharge process. Although p, i, and n layers were deposited in a single reaction chamber, the solar cell showed high‐energy conversion efficiency of 8.29% under AM1, 100‐mW/cm2 insolation. The distribution of boron atoms in the solar cell was analyzed by secondary ion mass spectroscopy. The boron content in the i layer was of the order of 1016 cm−3. This is comparable to that in the i layer of the solar cell fabricated by the glow discharge system with separated three reaction chambers.

By using Pauling's tetrahedral covalent radii, the procedure for choosing the pair of a III‐V compound semiconductor and a III‐V alloy semiconductor with good lattice match is discussed in general. When a III‐V compound is given for a substrate crystal, the composition of the alloy to be grown with the best lattice match on the substrate is easily determined from the fundamental equations derived in this study. It is demonstrated that for the GaAs substrate the grown alloy should be AlxGa1−xAs (if the alloy contains no P), or AlxGa0.5−xIn0.5P (if the V atoms in the alloy are P atoms only).

A ZnSe‐ZnTe strained‐layer superlattice (SLS) was grown on an InP substrate by molecular beam epitaxy for the first time. The x‐ray diffraction measurement technique was used to confirm the existence of the high quality SLS structure. Overall quality may also be inferred from the observed quantum size effects of the photoluminescence data.