Diffusion effects in short-channel GaAs MESFETs are studied using a two-dimensional electron temperature simulation. A structure that consists of two n + − n contacts on a thin channel region was used as a test vehicl...
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Diffusion effects in short-channel GaAs MESFETs are studied using a two-dimensional electron temperature simulation. A structure that consists of two n + − n contacts on a thin channel region was used as a test vehicle for the study. This structure was found to have a higher cutoff frequency than conventionally doped devices with the same gate length due to decreased gate capacitance and a selective modulation of the device transconductance. These results suggest that the performance of short-channel microwave MESFETs may be influenced strongly by electron diffusion.
We have investigated the dependence of the performance characteristics of In0.52 Al0.48As/ In0.53 Ga0.47 As resonant tunneling diodes upon molecular‐beam‐epitaxial growth parameters. The roughness of the growth fron...
We have investigated the dependence of the performance characteristics of In0.52 Al0.48As/ In0.53 Ga0.47 As resonant tunneling diodes upon molecular‐beam‐epitaxial growth parameters. The roughness of the growth front, leading to intrawell‐size fluctuations and the V/III flux ratio at a fixed growth temperature are found to be important parameters affecting the performance of these devices. By means of a simple model, we have semiquantitatively related the peak current to the interface roughness. Defects and traps in the In0.52 Al0.48 As barriers, on the other hand, produced partially by nonoptimal V/III flux ratios, may produce shunt paths for tunneling, again reducing the resonant tunneling current peak‐to‐valley ratio. Under optimum growth conditions we have measured current peak‐to‐valley ratios of 6.1 and 21.6 at 300 and 77 K, respectively. These are the best values reported so far for this heterostructure system.
The transient analysis of heterojunction bipolar transistors (HBTs) using the Monte Carlo technique is presented. Three HBT structures with conventional (A), inverted field (B), and undoped (C) collectors were simulat...
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The transient analysis of heterojunction bipolar transistors (HBTs) using the Monte Carlo technique is presented. Three HBT structures with conventional (A), inverted field (B), and undoped (C) collectors were simulated. The transient behavior of the collector currents show that the time constants are 1.466, 0.722, and 0.863 ps at a collector current of 3.5*10/sup 4/ A/cm/sup 2/ for devices A, B and C, respectively. This suggests that the inverted field structure may be the best choice for high-speed applications.< >
The DC and microwave properties of strained In/sub 0.65/Ga/sub 0.35/As/In/sub 052/Al/sub 0.48/As HEMTs (high electron-mobility transistors) with double-heterojunction design are presented. The high sheet carrier densi...
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The DC and microwave properties of strained In/sub 0.65/Ga/sub 0.35/As/In/sub 052/Al/sub 0.48/As HEMTs (high electron-mobility transistors) with double-heterojunction design are presented. The high sheet carrier density and good carrier confinement give rise to excellent device performance with very low output conductance. For 1*150- mu m/sup 2/ long-gate HEMTs, the measured cutoff frequency f/sub T/ and maximum frequency of oscillation f/sub max/ are as high as 37 and 66 GHz, respectively.< >
High-speed Ino.53Gao.47As and GaAs photodiodes with varying absorption region thicknesses were grown by molecular beam epitaxy on semi-insulating InP and GaAs substrates, respectively. The fabricated devices exhibit m...
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In the search of a high quality thin inter-polysilicon dielectric which has high breakdown voltage and low leakage current for high density non-volatile memory applications, thin (150Å) inter-polysilicon reoxidiz...
In the search of a high quality thin inter-polysilicon dielectric which has high breakdown voltage and low leakage current for high density non-volatile memory applications, thin (150Å) inter-polysilicon reoxidized nitrided oxide capacitors were fabricated with multiple rapid thermal processing. While rapid thermal nitridation degraded the breakdown field if compared to the rapid thermal oxide capacitors, rapid thermal reoxidation greatly enhanced the dielectric strength of the rapid thermal nitrided samples. The short reoxidations increased the film thickness by less than 10 Å. Breakdown field of optimized inter-polysilicon RTO/RTN/RTO capacitors up to 14 MV/cm has been measured.
Two different integration schemes for front-end optical receivers have been demonstrated for GaAs- and InP-based material systems. An InP-based p-i-n FET vertically integrated circuit exhibits a bandwidth greater than...
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Two different integration schemes for front-end optical receivers have been demonstrated for GaAs- and InP-based material systems. An InP-based p-i-n FET vertically integrated circuit exhibits a bandwidth greater than 2 GHz. The FET exhibits an extrinsic g/sub m/=450 mS/mm and f/sub T/=9 GHz. The GaAs-based planar structure consists of a modulated-barrier photodiode and a doped channel FET made with the same epitaxial layers. The detector has an optical gain of 200, and the FET performance is characterized by g/sub m/=250 mS/mm, f/sub T/=12 GHz, and f/sub max/=21 GHz.< >
Transport of carriers generated under the influence of optically induced spatial modulation is investigated theoretically and experimentally in semiconductors. The resulting transient photocurrent is studied under var...
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Transport of carriers generated under the influence of optically induced spatial modulation is investigated theoretically and experimentally in semiconductors. The resulting transient photocurrent is studied under varied degrees of optical interference. It is shown that strong anisotropic properties describable by an interaction tensor are suitable for device applications. Device properties are characterized and are seen to be useful for the processing of optical signals with picosecond and femtosecond features. Accurate modeling demonstrates the formation of strong nodal fields whose effect is detrimental to the achievement of high current extinction. The manifestation of interference-induced carrier modulation is demonstrated with high-contrast recordings of autocorrelation of picosecond laser pulses in homogeneous materials. In other experiments, monitoring of laser coherence ranging from picoseconds to tens of femtoseconds is shown.< >
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