- Email: [email protected]
InP DHBT in common base configuration on GaAs substrates
Materials Science in Semiconductor Processing 4 (2001) 647–649
High-frequency performance of metamorphic InP/ In0.53Ga0.47As/InP DHBT in common base configuration on GaAs substrates Yong Zhong Xiong*, Jeffrey S. Fu, Hong Wang, Geok-Ing Ng, K. Radhakrishnan Microelectronics Centre, School of Electrical and Electronics Engineering, Nanyang Technological University, Singapore, 639798 Singapore
Abstract In this work, we report the detailed high-frequency noise and power characterization of metamorphic InP double heterojunction bipolar transistors in common base configuration. The noise and power performances were investigated for 5 10 mm2 device. A minimum noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz, and a maximum output power of 13.0 dBm with a power added efficiency of 47.8% at 2.4 GHz were obtained. r 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction InP/InGaAs heterojunction bipolar transistors (HBTs) lattice matched (LM) to InP have demonstrated excellent microwave and noise performance compared to the commonly used GaAs HBTs due to the superior transport properties of InGaAs and the low surface recombination velocity of the InP/InGaAs material system [1,2]. For example, a world-record fmax of B800 GHz has been reported [3]; an InP HBT with a low noise figure of 0.46 dB at 2 GHz has also been demonstrated [4]. However, InP-based HBTs have several device and substrate processing limitations such as difficulties in substrate handling, smaller wafer size and higher cost. By growing InP/InGaAs HBT on GaAs substrate, these substrate-related issues can be eliminated. Recently, W. Hong et al. have demonstrated the first metamorphic (MM) InP double heterojunction bipolar transistor (DHBT) [5] with encouraging microwave performance. In this work, we report the detailed high-frequency noise and power characterization of MM InP DHBTs in common base configuration. A minimum *Corresponding author. VLSI Department, Institute of Microelectronics, Singapore 117685, Singapore. Tel.: +65770-5379; fax: +65-774-5754. E-mail address: [email protected] (Y.Z. Xiong).
noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz, and a maximum output power of 13.0 dBm with a power added efficiency (PAE) of 47.8% at 2.4 GHz were obtained. 2. Device layer structure Table 1 lists the HBT layer structure that was grown metamorphically on a GaAs substrate by using solidsource MBE. The structure includes an InP emitter, an In0.53Ga0.47As base, and an In0.53Ga0.47As-InP composite collector. A linearly graded (x ¼ 0:48–1) InxGa1xP buffer layer is used to relieve the strain between GaAs and InP. Identical structure was grown on an InP substrate without the strain-relief buffer by using the same MBE apparatus. To reduce the current blocking, the layer design uses an InGaAs/InP composite collector structure with dipole doping at the InGaAs/InP interface [6]. Optical lithography and selective wet etching were used to fabricate the triple-mesa type DHBT device. Electron-beam evaporated TiPtAu were used for emitter, base and collector ohmic contacts [5,7]. 3. Measurement results The fabricated 5 10 mm2 device in common base configuration showed an average extrinsic peak trans-
1369-8001/01/$ - see front matter r 2002 Elsevier Science Ltd. All rights reserved. PII: S 1 3 6 9 - 8 0 0 1 ( 0 2 ) 0 0 0 3 5 - 5
Y.Z. Xiong et al. / Materials Science in Semiconductor Processing 4 (2001) 647–649
Table 1 Layer design for MM-HBTs
10
nþ ¼ 2 1019 cm3, 100 nm nþ ¼ 2 1019 cm3, 60 nm n ¼ 3 1017 cm3, 90 nm pþ ¼ 2 1019 cm3, 47 nm
VCB = 1 V IE = 1.00 mA IC = 0.98 mA
8
NFMIN (dB)
InGaAs cap InP cap InP emitter InGaAs base
20
15
6 10
3
InP subcollector InGaAs subcollector GaAs substrate
n ¼ 5 1015 cm , 40 nm (InGaAs) p ¼ 1 1018 cm3, 10 nm (InGaAs) n ¼ 1 1018 cm3, 10 nm (InP) n ¼ 5 1015 cm3, 290 nm (InP) nþ ¼ 5 1018 cm3, 8 nm nþ ¼ 5 1018 cm3, 450 nm S.I.FInP (Fe)
4 5 2
2
4
6
8
10
12
14
Frequency (GHz) Fig. 2. Minimum noise figure ðNFmin Þ and associated gain ðGA Þ vs. frequencies for an MM common base 5 10 mm2 device.
12
50
8
I C (m A)
6 4 2 0
IE = 0 mA
-2 -4
IE step 2 mA
-6 0
1
2
3
P(out) (dBm) & Gain (dB)
IE = 10 mA
10
P(out) (dBm) Gain (dB) PAE (%)
15 10 5
30
0
20
-5 VCB = 2.5 V IE = 10.0 mA IC = 9.80 mA
-10
10 0
-15 -20
-15
-10
-5
0
5
10
15
P (In) (dBm)
V CB (V) Fig. 1. Typical I2V characteristics of 5 10 mm2 MM-HBT in common base configuration.
40
PAE (%)
Collector
-1
GA (d B )
648
Fig. 3. Output power, associated gain ðGA Þ and PAE vs. frequencies for an MM common base 5 10 mm2 device.
PAE of 47.8% at 2.4 GHz at a bias of IC ¼ 9:8 mA and VCB ¼ 2:5 V was obtained. port-coefficient current gain of 0.98 with a low leakage current and a high common collector breakdown voltage (BVCBO > 15 V). The I2V characteristics for an MM DHBT with an emitter size of 5 10 mm2 are shown in Fig. 1. The measured S-parameters indicate a maximum oscillation frequency ðfmax Þ of 112 GHz for the device with an emitter size of 5 10 mm2. The high-frequency noise characterization was carried out from 2 to 14 GHz using an ATN NP5B noise parameter measurement system. Fig. 2 shows the minimum noise figure ðFmin Þ and the associated gain ðGass Þ as a function of frequency at a bias of IC ¼ 0:98 mA and VCB ¼ 1:0 V. A minimum noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz are obtained. As frequency increases to 14 GHz, the minimum noise figure increases to 6.5 dB and the associated gain decreases to 4 dB. Microwave power measurements on these HBTs were carried out using ATN LP1 load-pull system. Output power, associated gain ðGA Þ and PAE vs. frequencies for a 5 10 mm2 MM common base device are shown in Fig. 3. A maximum output power of 13.0 dBm with a
4. Conclusion The noise and power performance for MM InP/ In0.53Ga0.47As/InP DHBT in common base configuration on GaAs substrates are investigated. A minimum noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz, and a maximum output power of 13.0 dBm with a PAE of 47.8% at 2.4 GHz were obtained for 5 10 mm2 device. With continued improvement in MM growth technique, the performance of MM-HBTs is expected to be on par with that of LM-HBTs. It is believed that the MM InP DHBT will be widely applied in communications.
Acknowledgements The authors wish to thank Prof. S.F. Yoon, Mr. H.Q. Zheng, and Mr. C.L. Tan, for their helpful discussions.
Y.Z. Xiong et al. / Materials Science in Semiconductor Processing 4 (2001) 647–649
This work is supported by the grant under the National Science and Technology Board of Singapore and the Ministry of Education of Singapore funded project (JT MLC 2/98).
[4]
References [1] Danelon V, Aniel F, Benchimol JL, Mba J, Riet M, Crozat P, Vernet G, Adde R. Noise parameters of InP-based double heterojunction base–collector self-aligned bipolar transistors. IEEE Microwave Guided Wave Lett 1999;9:195–7. [2] Kobayashi KW, Cowles J, Tran LT, Gutierrez-Aitken A, Block TR, Oki AK, Streit DC. A 50-MHz-55-GHz multidecade InP-based HBT distributed amplifier. IEEE Microwave Guided Wave Lett 1997;7:353–5. [3] Rodwell M, Lee Q, Mensa D, Guthrie J, Betser Y, Martin SC, Smith RP, Jaganathan S, Mathew T, Krishnan P,
[5]
[6] [7]
649
Serhan C, Long S. Transferred-substrate heterojunction bipolar transistor integrated circuit technology. In: Proceedings of the 11th International Conference on Indium Phosphide and Related Materials, 1999. p. 169–74. Chen Y-K, Nottenburg RN, Panish MB, Hamm RA, Humphrey DA. Microwave noise performance of InP/ InGaAs heterostructure bipolar transistors. IEEE Electron Device Lett 1989;10:470–2. Wang H, Ng GI, Zheng H, Xiong YZ, Chua LH, Yuan K, Radhakrishnan K, Yoon SF. Demonstration of Aluminumfree metamorphic InP/In0.53Ga0.47As/InP double heterojunction bipolar transistors on GaAs substrates. IEEE Electron Device Lett 2000;21(9):379. McAlister SP, McKinnon WR, Driad R, Renaud AP. J Appl Phys 1997;82:5231–4. Zheng HQ, Radhakrishnan K, Wang H, Yuan KH, Yoon SF, Ng GI. Metamorphic InP/InGaAs double-heterojunction bipolar transistors on GaAs grown by molecular-beam epitaxy. Appl Phys Lett 2000;77(6):869–71.
High-frequency performance of metamorphic InP/ In0.53Ga0.47As/InP DHBT in common base configuration on GaAs substrates Yong Zhong Xiong*, Jeffrey S. Fu, Hong Wang, Geok-Ing Ng, K. Radhakrishnan Microelectronics Centre, School of Electrical and Electronics Engineering, Nanyang Technological University, Singapore, 639798 Singapore
Abstract In this work, we report the detailed high-frequency noise and power characterization of metamorphic InP double heterojunction bipolar transistors in common base configuration. The noise and power performances were investigated for 5 10 mm2 device. A minimum noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz, and a maximum output power of 13.0 dBm with a power added efficiency of 47.8% at 2.4 GHz were obtained. r 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction InP/InGaAs heterojunction bipolar transistors (HBTs) lattice matched (LM) to InP have demonstrated excellent microwave and noise performance compared to the commonly used GaAs HBTs due to the superior transport properties of InGaAs and the low surface recombination velocity of the InP/InGaAs material system [1,2]. For example, a world-record fmax of B800 GHz has been reported [3]; an InP HBT with a low noise figure of 0.46 dB at 2 GHz has also been demonstrated [4]. However, InP-based HBTs have several device and substrate processing limitations such as difficulties in substrate handling, smaller wafer size and higher cost. By growing InP/InGaAs HBT on GaAs substrate, these substrate-related issues can be eliminated. Recently, W. Hong et al. have demonstrated the first metamorphic (MM) InP double heterojunction bipolar transistor (DHBT) [5] with encouraging microwave performance. In this work, we report the detailed high-frequency noise and power characterization of MM InP DHBTs in common base configuration. A minimum *Corresponding author. VLSI Department, Institute of Microelectronics, Singapore 117685, Singapore. Tel.: +65770-5379; fax: +65-774-5754. E-mail address: [email protected] (Y.Z. Xiong).
noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz, and a maximum output power of 13.0 dBm with a power added efficiency (PAE) of 47.8% at 2.4 GHz were obtained. 2. Device layer structure Table 1 lists the HBT layer structure that was grown metamorphically on a GaAs substrate by using solidsource MBE. The structure includes an InP emitter, an In0.53Ga0.47As base, and an In0.53Ga0.47As-InP composite collector. A linearly graded (x ¼ 0:48–1) InxGa1xP buffer layer is used to relieve the strain between GaAs and InP. Identical structure was grown on an InP substrate without the strain-relief buffer by using the same MBE apparatus. To reduce the current blocking, the layer design uses an InGaAs/InP composite collector structure with dipole doping at the InGaAs/InP interface [6]. Optical lithography and selective wet etching were used to fabricate the triple-mesa type DHBT device. Electron-beam evaporated TiPtAu were used for emitter, base and collector ohmic contacts [5,7]. 3. Measurement results The fabricated 5 10 mm2 device in common base configuration showed an average extrinsic peak trans-
1369-8001/01/$ - see front matter r 2002 Elsevier Science Ltd. All rights reserved. PII: S 1 3 6 9 - 8 0 0 1 ( 0 2 ) 0 0 0 3 5 - 5
Y.Z. Xiong et al. / Materials Science in Semiconductor Processing 4 (2001) 647–649
Table 1 Layer design for MM-HBTs
10
nþ ¼ 2 1019 cm3, 100 nm nþ ¼ 2 1019 cm3, 60 nm n ¼ 3 1017 cm3, 90 nm pþ ¼ 2 1019 cm3, 47 nm
VCB = 1 V IE = 1.00 mA IC = 0.98 mA
8
NFMIN (dB)
InGaAs cap InP cap InP emitter InGaAs base
20
15
6 10
3
InP subcollector InGaAs subcollector GaAs substrate
n ¼ 5 1015 cm , 40 nm (InGaAs) p ¼ 1 1018 cm3, 10 nm (InGaAs) n ¼ 1 1018 cm3, 10 nm (InP) n ¼ 5 1015 cm3, 290 nm (InP) nþ ¼ 5 1018 cm3, 8 nm nþ ¼ 5 1018 cm3, 450 nm S.I.FInP (Fe)
4 5 2
2
4
6
8
10
12
14
Frequency (GHz) Fig. 2. Minimum noise figure ðNFmin Þ and associated gain ðGA Þ vs. frequencies for an MM common base 5 10 mm2 device.
12
50
8
I C (m A)
6 4 2 0
IE = 0 mA
-2 -4
IE step 2 mA
-6 0
1
2
3
P(out) (dBm) & Gain (dB)
IE = 10 mA
10
P(out) (dBm) Gain (dB) PAE (%)
15 10 5
30
0
20
-5 VCB = 2.5 V IE = 10.0 mA IC = 9.80 mA
-10
10 0
-15 -20
-15
-10
-5
0
5
10
15
P (In) (dBm)
V CB (V) Fig. 1. Typical I2V characteristics of 5 10 mm2 MM-HBT in common base configuration.
40
PAE (%)
Collector
-1
GA (d B )
648
Fig. 3. Output power, associated gain ðGA Þ and PAE vs. frequencies for an MM common base 5 10 mm2 device.
PAE of 47.8% at 2.4 GHz at a bias of IC ¼ 9:8 mA and VCB ¼ 2:5 V was obtained. port-coefficient current gain of 0.98 with a low leakage current and a high common collector breakdown voltage (BVCBO > 15 V). The I2V characteristics for an MM DHBT with an emitter size of 5 10 mm2 are shown in Fig. 1. The measured S-parameters indicate a maximum oscillation frequency ðfmax Þ of 112 GHz for the device with an emitter size of 5 10 mm2. The high-frequency noise characterization was carried out from 2 to 14 GHz using an ATN NP5B noise parameter measurement system. Fig. 2 shows the minimum noise figure ðFmin Þ and the associated gain ðGass Þ as a function of frequency at a bias of IC ¼ 0:98 mA and VCB ¼ 1:0 V. A minimum noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz are obtained. As frequency increases to 14 GHz, the minimum noise figure increases to 6.5 dB and the associated gain decreases to 4 dB. Microwave power measurements on these HBTs were carried out using ATN LP1 load-pull system. Output power, associated gain ðGA Þ and PAE vs. frequencies for a 5 10 mm2 MM common base device are shown in Fig. 3. A maximum output power of 13.0 dBm with a
4. Conclusion The noise and power performance for MM InP/ In0.53Ga0.47As/InP DHBT in common base configuration on GaAs substrates are investigated. A minimum noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz, and a maximum output power of 13.0 dBm with a PAE of 47.8% at 2.4 GHz were obtained for 5 10 mm2 device. With continued improvement in MM growth technique, the performance of MM-HBTs is expected to be on par with that of LM-HBTs. It is believed that the MM InP DHBT will be widely applied in communications.
Acknowledgements The authors wish to thank Prof. S.F. Yoon, Mr. H.Q. Zheng, and Mr. C.L. Tan, for their helpful discussions.
Y.Z. Xiong et al. / Materials Science in Semiconductor Processing 4 (2001) 647–649
This work is supported by the grant under the National Science and Technology Board of Singapore and the Ministry of Education of Singapore funded project (JT MLC 2/98).
[4]
References [1] Danelon V, Aniel F, Benchimol JL, Mba J, Riet M, Crozat P, Vernet G, Adde R. Noise parameters of InP-based double heterojunction base–collector self-aligned bipolar transistors. IEEE Microwave Guided Wave Lett 1999;9:195–7. [2] Kobayashi KW, Cowles J, Tran LT, Gutierrez-Aitken A, Block TR, Oki AK, Streit DC. A 50-MHz-55-GHz multidecade InP-based HBT distributed amplifier. IEEE Microwave Guided Wave Lett 1997;7:353–5. [3] Rodwell M, Lee Q, Mensa D, Guthrie J, Betser Y, Martin SC, Smith RP, Jaganathan S, Mathew T, Krishnan P,
[5]
[6] [7]
649
Serhan C, Long S. Transferred-substrate heterojunction bipolar transistor integrated circuit technology. In: Proceedings of the 11th International Conference on Indium Phosphide and Related Materials, 1999. p. 169–74. Chen Y-K, Nottenburg RN, Panish MB, Hamm RA, Humphrey DA. Microwave noise performance of InP/ InGaAs heterostructure bipolar transistors. IEEE Electron Device Lett 1989;10:470–2. Wang H, Ng GI, Zheng H, Xiong YZ, Chua LH, Yuan K, Radhakrishnan K, Yoon SF. Demonstration of Aluminumfree metamorphic InP/In0.53Ga0.47As/InP double heterojunction bipolar transistors on GaAs substrates. IEEE Electron Device Lett 2000;21(9):379. McAlister SP, McKinnon WR, Driad R, Renaud AP. J Appl Phys 1997;82:5231–4. Zheng HQ, Radhakrishnan K, Wang H, Yuan KH, Yoon SF, Ng GI. Metamorphic InP/InGaAs double-heterojunction bipolar transistors on GaAs grown by molecular-beam epitaxy. Appl Phys Lett 2000;77(6):869–71.