Impact of surface layer on In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP high electron mobility transistors

Pao, Y.C.; Nishimoto, C.; Riaziat, M.; Majidi-Ahy, R.; Bechtel, Nina; Harris, Jason S.

doi:10.1109/55.56485

Cited by 26 publications

(4 citation statements)

References 9 publications

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“…3, fT showed an almost constant frequency of about 100 GHz above a wt of about 100-μm. Below this wt fT showed a slight increase with wt owing to the y-axis intercept effect of Cgd, as observed in many earlier studies [23,24]. Since f max is a strong function of R g as shown in Eq.…”

Section: ⅲ Analysis Of Device Scalingsupporting

confidence: 77%

Scaling Rules for Multi-Finger Structures of 0.1-μm Metamorphic High-Electron-Mobility Transistors

Ko¹,

Park²

2013

Journal of electromagnetic engineering and science

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We examined the scaling effects of a number of gate_fingers (N) and gate_widths (w) on the high-frequency characteristics of 0.1-μm metamorphic high-electron-mobility transistors. Functional relationships of the extracted small-signal parameters with total gate widths (wt) of different N were proposed. The cut-off frequency (fT) showed an almost independent relationship with wt; however, the maximum frequency of oscillation (fmax) exhibited a strong functional relationship of gate-resistance (Rg) influenced by both N and wt. A greater wt produced a higher fmax; but, to maximize fmax at a given wt, to increase N was more efficient than to increase the single gate_width.

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Section: ⅲ Analysis Of Device Scalingsupporting

confidence: 77%

Scaling Rules for Multi-Finger Structures of 0.1-μm Metamorphic High-Electron-Mobility Transistors

Ko¹,

Park²

2013

Journal of electromagnetic engineering and science

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“…The dependence of the dc characteristics on the gate-recess structure can be explained by the presence of surface states. [12][13][14][15][16][17][18] In the wide gate-recess structure, the negatively charged surface states decrease the n s by modulating the electric potential inside the channel, [14][15][16][17][18] as shown in Fig. 3a.…”

Section: Resultsmentioning

confidence: 99%

Effects of Gate-Recess Structure on High-Frequency Characteristics of 0.1 μm Metamorphic HEMTs

Baek

Lim

et al. 2007

J. Electrochem. Soc.

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We investigate effects of the gate-recess structure on the high-frequency characteristics of the 0.1 m depletion-mode metamorphic high electron mobility transistors ͑HEMTs͒. We characterize the dc and radio frequency performances of two different gate-recess structures and perform a comparative study using the hydrodynamic device model simulation and small-signal parameter analysis. The narrow gate-recess structure shows significantly higher dc performances than the wide gate-recess structure, and this phenomenon is due to the presence of the negatively charged surface states on the InAlAs Schottky barrier layer surface in the wide gate-recess structure. Despite the superior dc characteristics, the narrow gate-recess structure shows more degraded maximum frequency of oscillation ͑ f max ͒ of ϳ296 GHz than that ͑ϳ340 GHz͒ of the wide gate-recess structure and almost the same cutoff frequency ͑ f T ͒ of ϳ130 GHz. The degraded f max of the narrow gate-recess structure is attributed to a ϳ66% higher gate-to-drain capacitance ͑C gd ͒. The significant increase of C gd is caused by the reduction of effective gate-to-drain spacing due to the nonlinear electric potential distribution in the gate-to-drain region.

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“…In the wide gate-recess structure, negatively charged surface states on the InAlAs Schottky barrier layer decrease the sheet charier density ͑n s ͒ by modulating the electric potential inside the channel, [8][9][10][11][12][13][14][15] as shown in Fig. 1b.…”

Section: Resultsmentioning

confidence: 99%

Dual Gate-Recess Structure of Metamorphic High-Electron-Mobility Transistors for Enhancing f[sub max]

Han

Moon

et al. 2008

J. Electrochem. Soc.

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We present a gate-recess structure for 0.1 m metamorphic high-electron-mobility transistors to enhance the maximum frequency of oscillation ͑ f max ͒. Among the established gate-recess structures, the narrow gate-recess structure shows a degraded f max , despite superior dc characteristics due to a large gate-to-drain capacitance ͑C gd ͒ caused by a small effective gate-to-drain spacing, while the wide gate-recess structure exhibits lower dc characteristics due to the surface effects. To minimize C gd and maintain the dc characteristics of the narrow gate-recess structure, an additional gate-recess is performed for an electrical isolation between the drain side cap layer and drain electrode. We obtain almost the same extrinsic transconductance of ϳ600 mS/mm from this, while we achieve ϳ18% enhancement of f max ͑ϳ317 GHz͒ due to ϳ16% reduction of C gd by the increase of effective gate-to-drain spacing compared to the narrow gate-recess structure.High-electron-mobility transistors ͑HEMTs͒ have been used as essential devices for state-of-the-art millimeter-wave application systems, but device requirements, especially for the radio frequency ͑rf͒ performance, becomes tighter in highly sophisticated modern applications. 1-3 The cutoff frequency ͑ f T ͒ and maximum frequency of oscillation ͑ f max ͒ are important figures of merit for evaluating the rf characteristics of HEMTs, and they can be expressed by the following 4where g m,int , C gs , G ds , R i , R s , R g , and C gd represent intrinsic transconductance, gate-to-source capacitance, drain output conductance, intrinsic resistance, source resistance, gate resistance, and gate-todrain capacitance, respectively. The f max is often preferred to f T for characterizing high-frequency devices, because f max takes into account the losses associated with R g and G ds . Another reason for choosing f max in the evaluation of millimeter-wave transistors comes from the device scaling properties. The f max enhancement can be achieved by optimizing the small-signal parameters and increasing dc characteristics, 5 and there are many process-related variables critically affecting the dc characteristics and small-signal parameters. Among them, the gate-recess structure is one of the most sensitive and critical factors. 4,6,7 The gate-recess determines a suitable physical distance between the gate electrode and the channel layer by removing the doped cap layer. There are two distinctive gate-recess methods: one is the socalled "wide gate-recess," where we remove the entire cap layer exposed between the source-and-drain electrode ͑Fig. 1b͒, and the other is a "narrow gate-recess," where we remove only the gatefoot-landing region ͑Fig. 1c͒. In our earlier work, 8 a comparative study was performed on two different gate structures by examining the dc and rf characteristics of 0.1 m metamorphic HEMTs ͑MHEMTs͒. From this, the narrow gate-recess structure showed higher maximum drain-source saturation current ͑I dss,max ͒ and maximum extrinsic transconductance ͑g m,max ͒ over 40 and 20%, r...

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Impact of surface layer on In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP high electron mobility transistors

Cited by 26 publications

References 9 publications

Scaling Rules for Multi-Finger Structures of 0.1-μm Metamorphic High-Electron-Mobility Transistors

Scaling Rules for Multi-Finger Structures of 0.1-μm Metamorphic High-Electron-Mobility Transistors

Effects of Gate-Recess Structure on High-Frequency Characteristics of 0.1 μm Metamorphic HEMTs

Dual Gate-Recess Structure of Metamorphic High-Electron-Mobility Transistors for Enhancing f[sub max]

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