Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz

V. Kumar, G. Chen, S. Guo, B. Peres, I. Adesida

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

AlGaN/GaN high electron mobility transistors (HEMTs) are excellent candidates for high power and high frequency applications at room and elevated temperatures due to their superior material properties. As a result of improved material growth and processing technologies, microwave power densities have been demonstrated that are five to ten times greater than that of corresponding GaAs-based devices. Though GaN HEMTs using field plate have demonstrated power densities as high as 32W/mm at 4 GHz, however to date, there have been only few reports on field-plated devices up to X band [1,2]. In this paper, we present record power performance of AlGaN/GaN HEMTs on 6H-SiC substrates at 18 GHz. A CW output power density of 9.1 W/mm with a gain of 5.8 dB and power added efficiency of 23.7 % were achieved. The AlGaN HEMT structure used in the present study was grown on 6H-SiC substrates by metal organic chemical vapor deposition (MOCVD). The epilayer consists of an AlN buffer, 1.5 μm undoped GaN, and a 20 nm Al .30Ga .70N barrier layer. Average sheet resistance across the as-grown wafer was 380 Ω/sq as measured by Leighton. Device fabrication started with mesa isolation using Cl 2/Ar plasma in an inductively-coupled-plasma reactive ion etch (ICP-RIE) system. Alloyed ohmic contacts of Ti/Al/Mo/Au were formed at 850°C with a low contact resistance of ∼ 0.15 ohm-mm. The source-drain spacing for these devices was 2.7 μm. Next, silicon nitride was deposited using PECVD system. Then 0.25 μm gate-footprints were patterned using e-beam lithography and etched through the silicon nitride film in a RIE system. The distance between the gate-footprint and source contact was 0.8 μm for all transistors. Finally, Ni/Au (300/2500 Å) gamma-gates with different side-lobe lengths on the drain side were deposited by e-beam evaporation. Three side-lobe (field-plate) lengths were designed: 0.9, 1.2, and 1.5 μm. The devices had a total gate width of 100 μm. On-wafer DC measurements were performed using an HP4145B semiconductor parameter analyzer. Devices with different lengths of field plates had similar dc characteristics. Figure 1 shows a typical drain current-voltage (I D-V DS) characteristics for the device with a field plate length (L FP) of 1.5 μm. The gate was biased from -5 V to 2 V in a step of 1 V. The devices exhibited a maximum drain current density (I D,max) of 1.42 A/mm at a gate bias of 2 V and a drain bias of 9 V. The DC transfer characteristics for this device are shown in Fig. 2. The drain was biased at 7 V. A peak extrinsic transconductance (g m of 437 mS/mm was measured at V gs = -3.2 V. The high value of g m is attributed to the thin AlGaN barrier layer and the low contact resistance. On-wafer small signal RF measurements were carried out using a Cascade Microtech Probe and an HP8510C network analyzer. With the increase of field plate length from 0.9 to 1.5 μm, the cut-off frequency (f T) decreased from 50 to 41 GHz while the maximum frequency of oscillation (f max) degraded from 81 to 63 GHz. This is attributed to an increase in the gate-drain capacitance. Figure 3 shows the small signal RF performance of the device with the field plate length (L FP) of 1.5 μm. Large signal CW measurements at 18 GHz were performed using a Focus Microwave automatic load pull system. The data were taken on-wafer at room temperature without any thermal management. At a drain bias of 40 V, power densities of 5.4, 6.4 and 7.3 W/mm were measured for devices with L FP of 0.9, 1.2 and 1.5 μm, respectively. Large signal performance of the device with LFP of 1.5 μm at a drain bias of 55 V is shown in Fig. 4. The device has an output power of 29.57 dBm corresponding to 9.1 W/mm with an associated gain of 5.8 dB and PAE of 23.7 %. In summary, we have presented the CW power performance of 0.25 μm gate-length AlGaN/GaN HEMTs with field plates at 18 GHz. These results demonstrate the exceptional potential of these devices for hieh oower aonlications bevond X band.

Original languageEnglish
Title of host publication63rd Device Research Conference Digest, DRC'05
Pages61-62
Number of pages2
Volume2005
DOIs
Publication statusPublished - 2005
Externally publishedYes
Event63rd Device Research Conference, DRC'05 - Santa Clara, CA, United States
Duration: Jun 20 2005Jun 22 2005

Other

Other63rd Device Research Conference, DRC'05
CountryUnited States
CitySanta Clara, CA
Period6/20/056/22/05

Fingerprint

High electron mobility transistors
Drain current
Contact resistance
Silicon nitride
Microwaves
Electric network analyzers
Ohmic contacts
Epilayers
Sheet resistance
Organic chemicals
Reactive ion etching
Cutoff frequency
Transconductance
Inductively coupled plasma
Substrates
Plasma enhanced chemical vapor deposition
Temperature control
Lithography
Chemical vapor deposition
Materials properties

ASJC Scopus subject areas

  • Engineering(all)

Cite this

Kumar, V., Chen, G., Guo, S., Peres, B., & Adesida, I. (2005). Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz. In 63rd Device Research Conference Digest, DRC'05 (Vol. 2005, pp. 61-62). [1553055] https://doi.org/10.1109/DRC.2005.1553055

Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz. / Kumar, V.; Chen, G.; Guo, S.; Peres, B.; Adesida, I.

63rd Device Research Conference Digest, DRC'05. Vol. 2005 2005. p. 61-62 1553055.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Kumar, V, Chen, G, Guo, S, Peres, B & Adesida, I 2005, Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz. in 63rd Device Research Conference Digest, DRC'05. vol. 2005, 1553055, pp. 61-62, 63rd Device Research Conference, DRC'05, Santa Clara, CA, United States, 6/20/05. https://doi.org/10.1109/DRC.2005.1553055
Kumar V, Chen G, Guo S, Peres B, Adesida I. Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz. In 63rd Device Research Conference Digest, DRC'05. Vol. 2005. 2005. p. 61-62. 1553055 https://doi.org/10.1109/DRC.2005.1553055
Kumar, V. ; Chen, G. ; Guo, S. ; Peres, B. ; Adesida, I. / Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz. 63rd Device Research Conference Digest, DRC'05. Vol. 2005 2005. pp. 61-62
@inproceedings{9f3a517a32c640ada32ea6923625e041,
title = "Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz",
abstract = "AlGaN/GaN high electron mobility transistors (HEMTs) are excellent candidates for high power and high frequency applications at room and elevated temperatures due to their superior material properties. As a result of improved material growth and processing technologies, microwave power densities have been demonstrated that are five to ten times greater than that of corresponding GaAs-based devices. Though GaN HEMTs using field plate have demonstrated power densities as high as 32W/mm at 4 GHz, however to date, there have been only few reports on field-plated devices up to X band [1,2]. In this paper, we present record power performance of AlGaN/GaN HEMTs on 6H-SiC substrates at 18 GHz. A CW output power density of 9.1 W/mm with a gain of 5.8 dB and power added efficiency of 23.7 {\%} were achieved. The AlGaN HEMT structure used in the present study was grown on 6H-SiC substrates by metal organic chemical vapor deposition (MOCVD). The epilayer consists of an AlN buffer, 1.5 μm undoped GaN, and a 20 nm Al .30Ga .70N barrier layer. Average sheet resistance across the as-grown wafer was 380 Ω/sq as measured by Leighton. Device fabrication started with mesa isolation using Cl 2/Ar plasma in an inductively-coupled-plasma reactive ion etch (ICP-RIE) system. Alloyed ohmic contacts of Ti/Al/Mo/Au were formed at 850°C with a low contact resistance of ∼ 0.15 ohm-mm. The source-drain spacing for these devices was 2.7 μm. Next, silicon nitride was deposited using PECVD system. Then 0.25 μm gate-footprints were patterned using e-beam lithography and etched through the silicon nitride film in a RIE system. The distance between the gate-footprint and source contact was 0.8 μm for all transistors. Finally, Ni/Au (300/2500 {\AA}) gamma-gates with different side-lobe lengths on the drain side were deposited by e-beam evaporation. Three side-lobe (field-plate) lengths were designed: 0.9, 1.2, and 1.5 μm. The devices had a total gate width of 100 μm. On-wafer DC measurements were performed using an HP4145B semiconductor parameter analyzer. Devices with different lengths of field plates had similar dc characteristics. Figure 1 shows a typical drain current-voltage (I D-V DS) characteristics for the device with a field plate length (L FP) of 1.5 μm. The gate was biased from -5 V to 2 V in a step of 1 V. The devices exhibited a maximum drain current density (I D,max) of 1.42 A/mm at a gate bias of 2 V and a drain bias of 9 V. The DC transfer characteristics for this device are shown in Fig. 2. The drain was biased at 7 V. A peak extrinsic transconductance (g m of 437 mS/mm was measured at V gs = -3.2 V. The high value of g m is attributed to the thin AlGaN barrier layer and the low contact resistance. On-wafer small signal RF measurements were carried out using a Cascade Microtech Probe and an HP8510C network analyzer. With the increase of field plate length from 0.9 to 1.5 μm, the cut-off frequency (f T) decreased from 50 to 41 GHz while the maximum frequency of oscillation (f max) degraded from 81 to 63 GHz. This is attributed to an increase in the gate-drain capacitance. Figure 3 shows the small signal RF performance of the device with the field plate length (L FP) of 1.5 μm. Large signal CW measurements at 18 GHz were performed using a Focus Microwave automatic load pull system. The data were taken on-wafer at room temperature without any thermal management. At a drain bias of 40 V, power densities of 5.4, 6.4 and 7.3 W/mm were measured for devices with L FP of 0.9, 1.2 and 1.5 μm, respectively. Large signal performance of the device with LFP of 1.5 μm at a drain bias of 55 V is shown in Fig. 4. The device has an output power of 29.57 dBm corresponding to 9.1 W/mm with an associated gain of 5.8 dB and PAE of 23.7 {\%}. In summary, we have presented the CW power performance of 0.25 μm gate-length AlGaN/GaN HEMTs with field plates at 18 GHz. These results demonstrate the exceptional potential of these devices for hieh oower aonlications bevond X band.",
author = "V. Kumar and G. Chen and S. Guo and B. Peres and I. Adesida",
year = "2005",
doi = "10.1109/DRC.2005.1553055",
language = "English",
isbn = "0780390407",
volume = "2005",
pages = "61--62",
booktitle = "63rd Device Research Conference Digest, DRC'05",

}

TY - GEN

T1 - Field-plated AlGaN/GaN HEMTs with power density of 9.1 W/mm at 18 GHz

AU - Kumar, V.

AU - Chen, G.

AU - Guo, S.

AU - Peres, B.

AU - Adesida, I.

PY - 2005

Y1 - 2005

N2 - AlGaN/GaN high electron mobility transistors (HEMTs) are excellent candidates for high power and high frequency applications at room and elevated temperatures due to their superior material properties. As a result of improved material growth and processing technologies, microwave power densities have been demonstrated that are five to ten times greater than that of corresponding GaAs-based devices. Though GaN HEMTs using field plate have demonstrated power densities as high as 32W/mm at 4 GHz, however to date, there have been only few reports on field-plated devices up to X band [1,2]. In this paper, we present record power performance of AlGaN/GaN HEMTs on 6H-SiC substrates at 18 GHz. A CW output power density of 9.1 W/mm with a gain of 5.8 dB and power added efficiency of 23.7 % were achieved. The AlGaN HEMT structure used in the present study was grown on 6H-SiC substrates by metal organic chemical vapor deposition (MOCVD). The epilayer consists of an AlN buffer, 1.5 μm undoped GaN, and a 20 nm Al .30Ga .70N barrier layer. Average sheet resistance across the as-grown wafer was 380 Ω/sq as measured by Leighton. Device fabrication started with mesa isolation using Cl 2/Ar plasma in an inductively-coupled-plasma reactive ion etch (ICP-RIE) system. Alloyed ohmic contacts of Ti/Al/Mo/Au were formed at 850°C with a low contact resistance of ∼ 0.15 ohm-mm. The source-drain spacing for these devices was 2.7 μm. Next, silicon nitride was deposited using PECVD system. Then 0.25 μm gate-footprints were patterned using e-beam lithography and etched through the silicon nitride film in a RIE system. The distance between the gate-footprint and source contact was 0.8 μm for all transistors. Finally, Ni/Au (300/2500 Å) gamma-gates with different side-lobe lengths on the drain side were deposited by e-beam evaporation. Three side-lobe (field-plate) lengths were designed: 0.9, 1.2, and 1.5 μm. The devices had a total gate width of 100 μm. On-wafer DC measurements were performed using an HP4145B semiconductor parameter analyzer. Devices with different lengths of field plates had similar dc characteristics. Figure 1 shows a typical drain current-voltage (I D-V DS) characteristics for the device with a field plate length (L FP) of 1.5 μm. The gate was biased from -5 V to 2 V in a step of 1 V. The devices exhibited a maximum drain current density (I D,max) of 1.42 A/mm at a gate bias of 2 V and a drain bias of 9 V. The DC transfer characteristics for this device are shown in Fig. 2. The drain was biased at 7 V. A peak extrinsic transconductance (g m of 437 mS/mm was measured at V gs = -3.2 V. The high value of g m is attributed to the thin AlGaN barrier layer and the low contact resistance. On-wafer small signal RF measurements were carried out using a Cascade Microtech Probe and an HP8510C network analyzer. With the increase of field plate length from 0.9 to 1.5 μm, the cut-off frequency (f T) decreased from 50 to 41 GHz while the maximum frequency of oscillation (f max) degraded from 81 to 63 GHz. This is attributed to an increase in the gate-drain capacitance. Figure 3 shows the small signal RF performance of the device with the field plate length (L FP) of 1.5 μm. Large signal CW measurements at 18 GHz were performed using a Focus Microwave automatic load pull system. The data were taken on-wafer at room temperature without any thermal management. At a drain bias of 40 V, power densities of 5.4, 6.4 and 7.3 W/mm were measured for devices with L FP of 0.9, 1.2 and 1.5 μm, respectively. Large signal performance of the device with LFP of 1.5 μm at a drain bias of 55 V is shown in Fig. 4. The device has an output power of 29.57 dBm corresponding to 9.1 W/mm with an associated gain of 5.8 dB and PAE of 23.7 %. In summary, we have presented the CW power performance of 0.25 μm gate-length AlGaN/GaN HEMTs with field plates at 18 GHz. These results demonstrate the exceptional potential of these devices for hieh oower aonlications bevond X band.

AB - AlGaN/GaN high electron mobility transistors (HEMTs) are excellent candidates for high power and high frequency applications at room and elevated temperatures due to their superior material properties. As a result of improved material growth and processing technologies, microwave power densities have been demonstrated that are five to ten times greater than that of corresponding GaAs-based devices. Though GaN HEMTs using field plate have demonstrated power densities as high as 32W/mm at 4 GHz, however to date, there have been only few reports on field-plated devices up to X band [1,2]. In this paper, we present record power performance of AlGaN/GaN HEMTs on 6H-SiC substrates at 18 GHz. A CW output power density of 9.1 W/mm with a gain of 5.8 dB and power added efficiency of 23.7 % were achieved. The AlGaN HEMT structure used in the present study was grown on 6H-SiC substrates by metal organic chemical vapor deposition (MOCVD). The epilayer consists of an AlN buffer, 1.5 μm undoped GaN, and a 20 nm Al .30Ga .70N barrier layer. Average sheet resistance across the as-grown wafer was 380 Ω/sq as measured by Leighton. Device fabrication started with mesa isolation using Cl 2/Ar plasma in an inductively-coupled-plasma reactive ion etch (ICP-RIE) system. Alloyed ohmic contacts of Ti/Al/Mo/Au were formed at 850°C with a low contact resistance of ∼ 0.15 ohm-mm. The source-drain spacing for these devices was 2.7 μm. Next, silicon nitride was deposited using PECVD system. Then 0.25 μm gate-footprints were patterned using e-beam lithography and etched through the silicon nitride film in a RIE system. The distance between the gate-footprint and source contact was 0.8 μm for all transistors. Finally, Ni/Au (300/2500 Å) gamma-gates with different side-lobe lengths on the drain side were deposited by e-beam evaporation. Three side-lobe (field-plate) lengths were designed: 0.9, 1.2, and 1.5 μm. The devices had a total gate width of 100 μm. On-wafer DC measurements were performed using an HP4145B semiconductor parameter analyzer. Devices with different lengths of field plates had similar dc characteristics. Figure 1 shows a typical drain current-voltage (I D-V DS) characteristics for the device with a field plate length (L FP) of 1.5 μm. The gate was biased from -5 V to 2 V in a step of 1 V. The devices exhibited a maximum drain current density (I D,max) of 1.42 A/mm at a gate bias of 2 V and a drain bias of 9 V. The DC transfer characteristics for this device are shown in Fig. 2. The drain was biased at 7 V. A peak extrinsic transconductance (g m of 437 mS/mm was measured at V gs = -3.2 V. The high value of g m is attributed to the thin AlGaN barrier layer and the low contact resistance. On-wafer small signal RF measurements were carried out using a Cascade Microtech Probe and an HP8510C network analyzer. With the increase of field plate length from 0.9 to 1.5 μm, the cut-off frequency (f T) decreased from 50 to 41 GHz while the maximum frequency of oscillation (f max) degraded from 81 to 63 GHz. This is attributed to an increase in the gate-drain capacitance. Figure 3 shows the small signal RF performance of the device with the field plate length (L FP) of 1.5 μm. Large signal CW measurements at 18 GHz were performed using a Focus Microwave automatic load pull system. The data were taken on-wafer at room temperature without any thermal management. At a drain bias of 40 V, power densities of 5.4, 6.4 and 7.3 W/mm were measured for devices with L FP of 0.9, 1.2 and 1.5 μm, respectively. Large signal performance of the device with LFP of 1.5 μm at a drain bias of 55 V is shown in Fig. 4. The device has an output power of 29.57 dBm corresponding to 9.1 W/mm with an associated gain of 5.8 dB and PAE of 23.7 %. In summary, we have presented the CW power performance of 0.25 μm gate-length AlGaN/GaN HEMTs with field plates at 18 GHz. These results demonstrate the exceptional potential of these devices for hieh oower aonlications bevond X band.

UR - http://www.scopus.com/inward/record.url?scp=33751328800&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33751328800&partnerID=8YFLogxK

U2 - 10.1109/DRC.2005.1553055

DO - 10.1109/DRC.2005.1553055

M3 - Conference contribution

SN - 0780390407

SN - 9780780390409

VL - 2005

SP - 61

EP - 62

BT - 63rd Device Research Conference Digest, DRC'05

ER -