摘要:

Molecular‐beam epitaxy (MBE) has been used to grow very high quality layers for the confinement and transport of electrons in heterostructure acoustic charge transport (HACT) devices. In this paper the HACT device concept is reviewed, details of the layer structure and growth techniques are presented, and the performance of transversal filters produced with this material are discussed. It is demonstrated that the MBE growth techniques and epilayer design are adequate to produce charge transport efficiencies in excess of 0.9999 on HACT devices 1 cm (3.3 μs) long with 480 sensing taps. Considerable effort has been made to produce epilayers meeting the extremely demanding requirements of this large area device, and some details of this effort are discussed.

ISSN:1071-1023    

DOI:10.1116/1.585069

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Unintentionalp‐type doping of GaAs films grown by gas source molecular‐beam epitaxy (GSMBE) was reduced to 2×1014cm−3with a room‐temperature hole mobility of 490 cm2/V s. Intentional Si doping of GaAs films grown by GSMBE, using an elemental Si source, yielded controlled carrier concentrations from 7×1014to 8×1018cm−3with 77 K mobilities from 62 700 to 2 500 cm2/V s. Residual carbon incorporation was reduced in AlGaAs by growing at 560 °C and using tri‐isobutylaluminum such that 77 K two‐dimensional electron gas mobilities as high as 88 600 cm2/V s were obtained. Our study of using trimethylgallium or a graphite filament as a carbon source forp‐type doping indicates that doping levels can be controlled in the range of 5×1016–1.5×1020cm−3with good hole mobility and surface morphology. Preliminary results show an undetectable diffusion of carbon in the AlGaAs/GaAs heterojunction bipolar transistor (HBT) structures with a base doping level as high as 1.5×1020cm−3, using carbon as ap‐type dopant, grown at a substrate temperature of 600 °C and annealed at 700 °C for 30 min.

ISSN:1071-1023    

DOI:10.1116/1.585070

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We report comprehensive high‐frequency characteristics of pseudomorphic InAlAs/InGaAs/InP modulation doped field effect transistors having thick, dislocation‐free channels with an In mole fraction compositionally graded tox=0.65 at the heterointerface. Grading was achieved by reducing the Ga effusion cell temperature during epitaxial growth. High‐frequencyS‐parameter measurements were performed on transistors having gate lengths ofLg=0.25 μm and showed significant increases in both transconductancegmand current gain cutoff frequencyfTwith increasing graded channel layer thickness. The best devices with a 30 nm channel havegm=720 mS/mm andfT=120 GHz. We give data on growth conditions, layer structure, and device electrical properties.

ISSN:1071-1023    

DOI:10.1116/1.585071

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We report in this paper the achievement of unprecedented high mobilities of 15 200 and 123 000 cm2/V s with carrier concentrations of 1.84×1012and 1.81×1012cm−2at 300 and 77 K, respectively, through the use of a novel channel design utilizing oppositely strained layers withx=0.25 and 0.80 in Ga1−xInxAs. We have shown experimentally that the critical layer thickness for highly strained Ga1−xInxAs can be effectively enhanced by using such stress compensated structure. This novel modulation‐doped heterostructure with very high electron mobility should find important implications in very high speed electronics.

ISSN:1071-1023    

DOI:10.1116/1.585072

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The double‐heterostructure optoelectronic switch (DOES) has been adapted to incorporate a graded index waveguide and a single quantum well active region. The structure was grown using molecular‐beam epitaxy (MBE). Broad area devices, fabricating using thermally evaporated contacts and wet chemical etching to define the devices, exhibited ideal switching characteristics with a 7:1.8 V contrast between the on and off‐states. As a laser, the best threshold current density obtained was 580 A/cm2for a 560 μm long device. Variation of efficiency and threshold with cavity length yielded optical losses of 11 cm−1and an internal efficiency of 43%.

ISSN:1071-1023    

DOI:10.1116/1.585073

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

MBE grown resonant tunneling diodes based on the lattice matched AlAs/GaAs and the pseudomorphic AlGaAs/InGaAs systems are investigated. In the presence of quantizing magnetic field, a large number of tunneling peaks in the valley region of the current–voltage curves are observed. The dependence of the peak positions on magnetic field is used to distinguish direct tunneling between Landau levels from that due to phonon assisted tunneling. Shubnikov de‐Haas measurements show the evidence of a two‐dimensional quasibound state in the accumulation layer of the emitter and LO phonon assisted tunneling through the Landau levels in the well.

ISSN:1071-1023    

DOI:10.1116/1.585074

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Studies have been conducted of isoelectronic In doping inn‐GaAs andp‐GaAs grown by molecular beam epitaxy. The concentration of most of the electron and hole traps are suppressed by up to three orders of magnitude by introducing 0.2–1 at. % In and increasing growth temperatures from 500 to 550 °C. As a result an improvement in minority carrier lifetime and diffusion length is achieved. This is demonstrated by the comparison ofpnpandnpnGaAs homojunction transistors grown with and without In doping in base layers. Based on these results,pnpnGaAs homojunction thyristors were designed and fabricated with and without In doping in the middlenandp‐GaAs layers. More than a factor of 2 reduction in the trigger current was observed as a result of the In doping.

ISSN:1071-1023    

DOI:10.1116/1.585075

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Previously, solar cells fabricated from molecular‐beam epitaxually (MBE)‐grown material have been inferior in performance to those fabricated from metalorganic chemical vapor deposited (MOCVD) material. We have obtained 1‐sun air mass (AM) 1.5 efficiencies of 23.8% for 0.25 cm2GaAs solar cells fabricated on MBE‐grown material. This is the first solar cell fabricated on MBE material which is of comparable performance to solar cells fabricated on MOCVD material. Details of the MBE system preparation and film growth procedure along with a detailed evaluation of the solar cells will be presented.

ISSN:1071-1023    

DOI:10.1116/1.585031

出版商:American Vacuum Society    

年代:1990

数据来源: AIP