摘要:

The first high‐resolution study of the optical emission from nitrogen plasmas produced by an ASTeX compact electron cyclotron resonance (ECR) microwave plasma source is reported. The spectroscopic results clearly show that the ECR plasma source generates an appreciable flux of nitrogen atoms, as indicated by strong atomic emission lines in the near‐infrared spectral region, in addition to various species of molecular nitrogen.

ISSN:0734-211X    

DOI:10.1116/1.587052

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

We report the gated detection of reflection high‐energy electron diffraction (RHEED) signal intensity oscillations during molecular‐beam epitaxy (MBE) while the wafer is being rotated at high speed (≳100 rpm). In general, a larger number of oscillation periods are observed with this technique than during stationary measurement because of the very high growth rate uniformity across the sample. We found that the average over all azimuths of the RHEED specular spot intensity shows the same growth induced oscillations. This allowed us to replace the gated detection by an averaging detection method: a low‐pass filter suppresses fast variations due to rapid changes in azimuth, while passing low‐frequency (<1 Hz) growth related oscillations. This simplifies the detection system and at the same time reduces noise related to wafer motion, 60 Hz, etc. These techniques have potential use forinsitumonitoring of thickness and composition of device wafers.

ISSN:0734-211X    

DOI:10.1116/1.587053

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

We report on molecular beam epitaxial growth of Si doped, single and multiple quantum well structures. We have examined the effects of growth parameters such as substrate temperature, group V/III ratio, and intentional and unintentional impurities, on the electrical and optical properties of the quantum wells structures. Capacitance–voltage and secondary ion mass spectrometry analysis of the structures reveal that the net density of electrically active carriers in the wells is controlled by the number of acceptor states in the AlGaAs barrier. We have assigned the source of the acceptor state to the presence of oxygen in the AlGaAs barrier. We observe that the strength of the intersubband optical absorption from the quantum wells increases linearly with the Si‐doping in the well. Photoluminescence measurements indicate that for a given substrate temperature, a lower V/III ratio results in higher quality quantum well.

ISSN:0734-211X    

DOI:10.1116/1.587054

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A detailed analysis of the electrical and optical properties of GaSb–AlSb quantum well infrared photodetector structures is presented. Hall effect measurements were performed, and a two‐band conduction model was employed to extract the electron concentration in theLsubband, indicating that at typical detector operating temperaturesT=80 K there are at least 1012cm−2carriers in theLsubband. Temperature‐dependent dark current measurements indicate that the dark current mechanism in detector structures consists of a tunneling regime forT<100 K, and a thermionic regime forT≳100 K. An activation energy of 170 meV is extracted from the temperature dependence of the thermionic dark current. Photoluminescence and absorption measurements were also used to obtain information on the subband levels relative to the bottom of the well, and to investigate the effect of doping on the quality of the GaSb quantum wells. We also report on a method to push the intersubband transition to longer wavelengths by growing center‐loaded structures in which a thin layer of AlSb is deposited in the center of the well in order to raise the energy ofonlythe ground state in the well.

ISSN:0734-211X    

DOI:10.1116/1.587055

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The growth of GaAs quantum well modulators on Si for photonic switching applications is reported. Comparison of modulator’s quantum confined Stark effect atop different miscut Si surfaces demonstrate the need for a highly ordered array of bilayer steps as an initial Si surface condition for heteroepitaxy. Proton implantation into the SiO2/Si system via an electron cyclotron resonance plasma to lower the Si oxide desorption temperature, while perserving step ordering of the surface, is explored.  

ISSN:0734-211X    

DOI:10.1116/1.587056

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Chemical beam epitaxy has been utilized to demonstrate high efficiency InGaAs/InP tandem solar cells on InP substrates. The key development in achieving such tandems is the growth of high peak current density InGaAs tunnel junctions for use as interconnect between the top and bottom cells. The growth and performance of the InGaAs bottom cell, the InGaAs tunnel junction, and the InP top cell are first independently presented in the paper. Then the growth of an InP‐based tandem cell is described followed by a discussion of its performance.

ISSN:0734-211X    

DOI:10.1116/1.587014

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

This article reports results involving the molecular beam epitaxial growth of the quaternary (Zn,Mg)(S,Se) compound as well as the incorporation of this quaternary into a pseudomorphic separate confinement heterostructure laser diode configuration. It was found that the quaternary (Zn,Mg)(S,Se) can accommodate much more strain as compared to binary ZnSe; the films remained essentially pseudomorphic, with low defect densities, for strains in the studied range from −0.225% (tension) to 0.137% (compression) at room temperature. The relationship between the surface morphology and the strain is also described in this paper. Lasing was routinely obtained at room temperature under pulsed injection. A threshold lasing voltage of as low as 7 V was observed in index‐guided diode lasers.

ISSN:0734-211X    

DOI:10.1116/1.587015

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Aninsituprocess which includes electron cyclotron resonance plasma etching and molecular beam epitaxial regrowth is applied to the fabrication of buried heterostructure vertical cavity surface‐emitting laser (SEL) diodes and edge‐emitting laser (EEL) diodes. The buried SEL with a 7.5 μm diameter has a pulsed laser threshold current of 1 mA, and a threshold voltage of 4 V with a peak power of 0.9 mW. The buried EEL with 2.5 μm stripe width and 800 μm cavity length has a threshold current density of 500 A/cm2.

ISSN:0734-211X    

DOI:10.1116/1.587016

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The first ZnSe–ZnCdSe double‐heterostructure light‐emitting diodes (LEDs) and photopumped laser structures on ZnSe substrates have been successfully grown by molecular beam epitaxy. The LEDs emit bright blue/green electroluminescence at room temperature, with the emission peak centered at 492 nm. Photopumped laser emission was also observed from ZnSe–ZnCdSe multiple‐quantum‐well structures grown on ZnSe substrates. The cleaved‐cavity devices display stimulated emission in the deep‐blue spectral region near 477 nm at 10 K and at 478.8 nm at 80 K.  

ISSN:0734-211X    

DOI:10.1116/1.587017

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Recent advances in the performance of GaInAsSb/AlGaAsSb quantum‐well diode lasers have been directly related to improvements in the quality of the molecular‐beam epitaxy (MBE)‐grown epitaxial layers. These improvements have been based on careful measurement and control of lattice matching and intentional strain, changes in shutter sequencing at interfaces, and a generally better understanding of the growth of Sb‐based epitaxial materials. By using this improved MBE‐grown material, significantly enhanced performance has been obtained for midinfrared lasers. These lasers, which are capable of ∼2‐μm emission at room temperature, presently exhibit threshold current densities of 143 A/cm2, continuous wave powers of 1.3 W, and diffraction‐limited powers of 120 mW. Such high‐performance midinfrared diode lasers are of interest for a wide variety of applications, including eye‐safe laser radar, remote sensing of atmospheric contaminants and wind turbulence, laser surgery, and pumping of solid‐state laser media.

ISSN:0734-211X    

DOI:10.1116/1.587018

出版商:American Vacuum Society    

年代:1994

数据来源: AIP