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ABSTRACT: We report the successful fabrication of ZnSe p‐n junction light‐emitting diodes in which Li and Cl are used as p‐type and n‐type dopants, respectively.
Applied Physics Letters 11/1990; · 3.84 Impact Factor
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ABSTRACT: We report the first demonstration of ZnSe metal‐semiconductor field‐effect transistors. These new devices were fabricated from n‐type Cl‐doped epitaxial ZnSe layers grown by molecular beam epitaxy on (100) oriented semi‐insulating Cr‐doped GaAs substrates. Epitaxial layers with room‐temperature carrier concentrations of 1.6×10<sup>17</sup> cm<sup>-3</sup> and electron mobilities ranging from 400 to 500 cm<sup>2</sup>/V s were used for device fabrication. Au was used as a Schottky gate contact. Either In or a multilevel metallization scheme using Cr and In was employed for the source and drain ohmic contacts. Depletion‐mode transistor operation was observed for structures with 5 and 100 μm gate lengths and varying gate widths. The 5 μm gate length by 200 μm gate width device structures exhibited transconductances of 0.5 mS/mm.
Applied Physics Letters 11/1990; · 3.84 Impact Factor
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ABSTRACT: The first demonstration of Hg 1-x Cd x Te metal–insulator‐semiconductor field‐effect transistors prepared using n‐type layers grown by photoassisted molecular beam epitaxy is reported. These transistor structures were processed by means of a new low‐temperature (≪60 °C) semiconductor device processing technology developed at North Carolina State University, and differ significantly from structures previously reported in that (1) a depletion region instead of a surface inversion layer is used as the principle for device operation, (2) larger x‐value Hg 1-x Cd x Te is employed as the active region of the device, and (3) the transistor structures are fabricated without the use of ion implantation and thermal annealing processing steps. In addition, the low‐temperature processing technology is compatible with the future development of superlattice and multilayer device structures consisting of Hg‐based alloys, in which mercury interdiffusion at heterointerfaces can significantly alter the material properties. Depletion and enhancement‐mode operation have been observed and digital inverter circuits have been characterized at speeds of 1 MHz.
Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 04/1990; · 1.25 Impact Factor
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ABSTRACT: We report the successful p‐type doping of CdTe films with arsenic using the photoassisted molecular beam epitaxy growth technique. These doped epilayers were grown at substrate temperatures as low as 180 °C. The room‐temperature hole concentrations in the CdTe:As layers ranged from 7×10<sup>1</sup><sup>5</sup> to 6.2×10<sup>1</sup><sup>8</sup> cm<sup>-</sup><sup>3</sup> as determined by van der Pauw–Hall effect measurements. We propose a doping mechanism responsible for the high p‐type doping levels observed in the films. The arsenic acceptor ionization energy was found to ∼58–60 meV using low‐temperature photoluminescence measurements.
Applied Physics Letters 02/1989; · 3.84 Impact Factor
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ABSTRACT: II-VI semiconductor surface passivants, insulators, and epitaxial films have been deposited onto selective surface areas by employing a new masking and lift-off technique. The II-VI layers were grown by either conventional or photoassisted molecular beam epitaxy (MBE). CdTe has been selectively deposited onto HgCdTe epitaxial layers as a surface passivant. Selective-area deposition of ZnS has been used in metal-insulator-semiconductor (MIS) structures. Low resistance ohmic contacts to p-type CdTe:As have also been realized through the use of selectively-placed thin films of the semi-metal HgTe followed by a thermal evaporation of In. Epitaxial layers of HgTe, HgCdTe, and HgTe-CdTe superlattices have also been grown in selective areas on CdZnTe substrates, exhibiting specular morphologies and double-crystal x-ray diffraction rocking curves (DCXD) with full widths at half maximum (FWHMs) as narrow as 140 arcseconds.
MRS Proceedings. 12/1988; 161.
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ABSTRACT: We report the first demonstration of electronic devices, Schottky diodes, and metal‐semiconductor field‐effect transistors, in a diluted magnetic semiconductor Cd 1-x Mn x Te. These devices were fabricated using n‐type, indium‐doped CdMnTe films grown by photoassisted molecular beam epitaxy on (100) CdTe and CdZnTe substrates. Epitaxial layers with carrier concentrations of 1×10<sup>1</sup><sup>7</sup> cm<sup>-</sup><sup>3</sup> and electron mobilities as large as 720 cm<sup>2</sup>/V s at 120 K were used. The Schottky diodes have turn‐on voltages of 0.8 V, idealities in the range between 1.27 and 1.7, and reverse breakdown voltages from 5.5 to 10.5 V reverse bias. The 100 μm gate length transistors have transconductances of 1 mS/mm.
Applied Physics Letters 11/1988; · 3.84 Impact Factor
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ABSTRACT: Interest in CdTe field effect transistors and multigated devices stems from the fact that CdTe is lattice matched to HgCdTe. As a consequence, it may be possible to develop a monolithic technology that combines HgCdTe infrared focal plane arrays with on‐board signal processing based on CdTe devices. Although CdTe metal–semiconductor field effect transistors have only recently been fabricated for the first time, rapid improvements in device performance have been realized. All of the devices studied to date have employed CdTe:In epilayers grown by photoassisted molecular‐beam epitaxy. Here we report devices having gold Schottky barriers with reverse breakdown voltages as high as 13.5 V and ideality factors approaching 1.2 which exhibit good depletion mode transistor action. Also, carrier concentrations determined by capacitance–voltage measurements agree with Hall‐effect measurements.
Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 08/1988; · 1.25 Impact Factor
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ABSTRACT: We report the first demonstration of CdTe metal‐semiconductor field‐effect transistors. These transistors were fabricated using n‐type CdTe films grown by photoassisted molecular beam epitaxy. Using this new film deposition technique, it is possible to obtain highly activated n‐type or p‐type films suitable for device applications. In the present work, transistor structures with 5 or 100 μm gate lengths having channel dopings in the range from 2×10<sup>1</sup><sup>6</sup> to 2×10<sup>1</sup><sup>7</sup> cm<sup>-</sup><sup>3</sup> were fabricated and tested. The 5 μm gate devices have transconductances as large as 10 mS/mm and pinch‐off voltages of 4.0 V.
Applied Physics Letters 10/1987; · 3.84 Impact Factor
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ABSTRACT: Several superlattice structures, grown by molecular beam epitaxy, have been used to reduce the density of threading dislocations originating from the GaAs substrate. Results clearly indicate that compared to epitaxial layers grown directly on GaAs substrates, a GaAs‐In x Ga 1-x As superlattice (x≪0.12) reduces the dislocations by approximately two orders of magnitude. Transmission electron microscopy, electron beam induced current, and etch pit density have been used to characterize the effectiveness of using superlattice buffer layers for the reduction of defects in GaAs epilayers.
Applied Physics Letters 11/1986; · 3.84 Impact Factor
