摘要:

Autocompensation has been studied on the (100) and (110) orientations of gallium arsenide. Bothn‐ andp‐type silicon‐doped (110) gallium arsenide films have been grown by only varying the substrate temperature. Electrical and optical data show thatn‐type (110) films are heavily autocompensated with silicon.

ISSN:1071-1023    

DOI:10.1116/1.582524

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

We have achieved the first successful growth of GaAs films with good electrical properties at substrate temperatures below 480 °C. The electrical and photoluminescence properties of films grown atTs≊380 and 450 °C have been dramatically improved by reducing the growth rate significantly below the usual rate of ∼1 μm/h. Reductions in the growth rate can be expected to improve the quality of MBE films by allowing sufficient time for Ga and As adatoms to jump to equilibrium lattice positions before they are incorporated into the growing crystal by interacting with other adatoms. We further observed that the density of a major morphological defect of MBE GaAs films—the oval defect—was strongly correlated with the growth rate. The density of such defects was ∼500 cm−2for films grown at ∼0.02 μm/h.

ISSN:1071-1023    

DOI:10.1116/1.582525

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The molecular beam epitaxial (MBE) growth of high quality Si‐doped (n‐type) and Be‐doped (p‐type) AlxGa1−xAs with 0

ISSN:1071-1023    

DOI:10.1116/1.582526

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The redistribution of Mn in MBE grown In0.53Ga0.47As layers containing different combinations of Mn and Ge doping pulses and subjected to various annealing conditions has been studied by secondary ion mass spectrometry (SIMS). The results indicate that Ge has a negligible diffusivity for temperatures up to 700 °C while the diffusion coefficient of Mn is approximately inversely proportional to the local Mn concentration. Accumulation of Mn in amounts proportional to the local Ge concentration has also been observed, suggesting the formation of donor–acceptor pairs with a certain fraction of Ge in the crystal. For those Mn atoms not immobilized by pairing, the diffusion coefficient is found to be reduced by nearly two orders of magnitude by the presence of Ge in the layer with very little dependence on the spatial distribution of Ge.

ISSN:1071-1023    

DOI:10.1116/1.582528

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Modulation‐doped FETs grown by MBE exhibit very high currents and transconductances per unit gate width. In short gate FETs the high transconductances are a result of large electron velocities; typically 2×107cm/s at 300 K and 3×107cm/s at 77 K. Since the low field mobility does not strongly affect device performance, improvements were obtained by adjusting the parameters of the heterostructure to maximize charge transfer across the heterojunction. An improved calculation of the maximum charge transfer is used to derive closed expressions for the maximum current and transconductance. Predictions of increasing current and transconductance as the undoped (Al,Ga)As spacer layer thickness is decreased have been verified by experimental results. For aN‐off FET with a 20 Å spacer layer transconductances as high as 250 mS/mm at 300 K and 400 mS/mm at 77 K have been obtained. Maximum currents as high as 200 and 300 mA/mm were obtained inN‐off andN‐on devices, respectively, at 300 K. In this paper the crystal growth, device fabrication, and design considerations for modulation‐doped FETs are discussed.

ISSN:1071-1023    

DOI:10.1116/1.582484

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Both normally on and normally off modulation‐doped FETs have been fabricated from MBE grown AlGaAs/GaAs heterojunction structures. The staticI–Vcharacteristics of recessed‐gate FETs were measured over the temperature range 77–400 K. A large change in the threshold voltageVtwith temperatureTwas observed. The observedVt(T) data are explained, in part, in terms of a simple model based on the temperature‐dependent occupation of deep donor traps in the AlGaAs layer. The traps were characterized by different energies for emission and capture. The transient capacitance of large area modulation‐doped Schottky diodes was also measured. The capacitance data is explained by the time‐dependent occupation of the same donor traps. The value of the activation energy for carrier emission was estimated to be 450 mV while the donor level was found to be about 42 mV below the conduction band.

ISSN:1071-1023    

DOI:10.1116/1.582485

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Thin layers of GaAs, heavily doped with Sn, Si, or Be, have been incorporated into Schottky barrier diode and bulk unipolar (camel) diode structures. The effective barrier height of the Schottky diodes has been varied between 0.48 and 0.96 eV by changing the doping and thickness of the heavily doped layer adjacent to the metal contact, and camel diodes with barriers between 0.55 and 0.94 eV have also been fabricated. There is a quantitative discrepancy between the experimental and theoretical diode parameters, however, and possible explanations are discussed.

ISSN:1071-1023    

DOI:10.1116/1.582486

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The technique of molecular beam epitaxy (MBE) was applied to the growth of millimeter‐wave GaAs double‐drift, flat‐profile IMPATT structures to meet the stringent doping concentration and thickness requirements. Each structure has five epitaxial layers and was prepared by first growing an undoped AlxGa1−xAs (x∼0.3) layer on a Cr‐doped, semi‐insulating GaAs(100) substrate held at 600 °C, followed by ann+‐GaAs (>1018cm−3) buffer layer, andn‐GaAs (>1017cm−3) layer, ap‐GaAs (>1017cm−3) layer, and a p+‐GaAs (>1018cm−3) contact layer. Si and Be were used asn‐type andp‐type dopants, respectively. The AlxGa1−xAs layer acts as an effective ‘‘etch stop’’ during device fabrication, allowing selective removal of the substrate from the epitaxially grown layers in order to reduce the device series resistance. Each device was fabricated with its own ‘‘integral packaging’’ and oscillated in microstrip resonators. The cw oscillations were obtained up to 109 GHz, which is the highest frequency achieved with double‐drift‐type GaAs IMPATTs.

ISSN:1071-1023    

DOI:10.1116/1.582487

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The band gap of Ga0.47In0.53As corresponds to an emission wavelength of ∼1.65 μm. Lasers have been produced with Al0.48In0.52As as cladding layers operating at room temperature. The peak emission of Ga0.47In0.53As can be continuously varied from 1.65 to 1.2 μm by the use of the multiquantum well structures. This range of wavelengths covers the minimum loss and dispersion in optical fibers and will be applicable to integrated optics. Double heterostructure broad area lasers have been fabricated using AlInAs as cladding layers to the GaInAs active layer. Room temperature threshold current densities of 4.3 kA/cm2have been obtained for lasers with a 4500 Å active regions. The first data on GaInAs/AlInAs quantum well emitters will be presented. 4 K photoluminescence from quantum well layers of 100, 150, and 180 Å with 150 Å AlInAs barrier layers produced emission at 1.27, 1.35, and 1.41 μm, respectively. Ga0.47In0.52As quantum well LED’s have also been produced which emit at 1.34 μm.

ISSN:1071-1023    

DOI:10.1116/1.582488

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.582489

出版商:American Vacuum Society    

年代:1983

数据来源: AIP