Explanation of anomalously high current gain observed in GaN based bipolar transistors

Xing, Huili Grace; Jena, Debdeep; Rodwell, M.J.W.; Mishra, Umesh K.

doi:10.1109/led.2002.807023

Cited by 22 publications

(9 citation statements)

References 13 publications

(12 reference statements)

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“…We have carried out a study on the measured device characteristics influenced by the presence of leakage currents and poor ohmic contacts. This study reveals that current gain peaks at low current levels are not the gain of the intrinsic device, but an artifact resulting from effect of base-collector leakage coupled with poor ohmic base contacts [11]. The intrinsic current gain of 18 is then determined at a higher current level of 9 mA (the corresponding average current density is 900 A cm ), where the leakage currents were measured to be negligible.…”

Section: Resultsmentioning

confidence: 90%

Very high voltage operation (>330 V) with high current gain of AlGaN/GaN HBTs

Xing

Chavarkar²,

Keller

et al. 2003

IEEE Electron Device Lett.

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Abstract-N-p-n Al 0 05 GaN/GaN heterojunction bipolar transistors with a common emitter operation voltage higher than 330 V have been demonstrated using selectively regrown emitters. Devices were grown by metalorganic chemical vapor deposition on sapphire substrates. The n-type emitter was grown selectively on a 100-nm-thick p-base with an 8 m n-collector structure using a dielectric mask. The shallow etch down to the collector mitigates damages induced in the dry etch, resulting a low leakage and a high breakdown. The graded AlGaN emitter results in a common emitter current gain of 18 at an average collector current density of up to 1 kA cm 2 at room temperature.

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Section: Resultsmentioning

confidence: 90%

Very high voltage operation (>330 V) with high current gain of AlGaN/GaN HBTs

Xing

Chavarkar²,

Keller

et al. 2003

IEEE Electron Device Lett.

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“…The ECR plasma was excited by the combination of 2.45 GHz microwave power and the magnetic field. 15 The current gain of the HBT after annealing increases monotonously with the increase of the collector current. The chamber pressure was kept at 5 mTorr during the deposition process.…”

Section: Methodsmentioning

confidence: 99%

“…15 A peak of current gain is typically found at the low collector current. If the leakage current of the basecollector junction is very large, it severely affects the I -V characteristics, especially for the double HBTs, which typically work at large base-collector reverse bias.…”

Section: B Origin Of Leakage Currentmentioning

confidence: 99%

Sulfur and low-temperature SiNx passivation of self-aligned graded-base InGaAs/InP heterostructure bipolar transistors

Jin

Prost

Neumann

et al. 2004

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Comparison of the passivation effects on self-and non-self-aligned InP/InGaAs/InP double heterostructure bipolar transistors by low-temperature deposited SiN x Base metallization stability in InP/InGaAs heterojunction bipolar transistors and its influence on leakage currentsThe passivation of self-aligned InGaAs/InP heterostructure bipolar transistors ͑HBTs͒ with graded base by the combination of S and low-temperature deposited SiN x was investigated. Base current was found to decrease after the passivation. Collector current significantly increases at low base-emitter voltages. The increase is attributed to the leakage current of the base-collector diode. The current gain was found to increase. When annealing was performed at 300°C for 5 min, the base current decreases further and the collector current decreases. The leakage of collector current was found to be suppressed. The current gain was further improved and the leakage current can affect the Gummel plots. The leakage source was identified to be the interface between the semiconductor and the SiN x layer. The leakage current can be decreased by the annealing process.

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“…Note that the relatively high value of the current gain at low current level is an artifact of the high base leakage current. [10][11] To further investigate the origin of the high series resistance, we compare the current-voltage characteristics of the emitter, base, and collector contacts of the device in Fig. 5.…”

Section: Emitter Growth and Designmentioning

confidence: 99%

Growth of InGaN HBTs by MOCVD

Chung

Limb

Ryou

et al. 2006

J. Electron. Mater.

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The design and growth of GaN/InGaN heterojunction bipolar transistors (HBTs) by metalorganic chemical vapor deposition (MOCVD) are studied. Atomic-force microscopy (AFM) images of p 1 InGaN base layers (;100 nm) deposited under various growth conditions indicate that the optimal growth temperature is limited to the range between 810 and 830°C due to a trade-off between surface roughness and indium incorporation. At these temperatures, the growth pressure must be kept above 300 Torr in order to keep surface pit density under control. An InGaN graded-composition emitter is adopted in order to reduce the number of V-shaped defects, which appear at the interface between GaN emitter and InGaN base and render an abrupt emitter-base heterojunction nearly impossible. However, the device performance is severely limited by the high p-type base contact resistance due to surface etching damage, which resulted from the emitter mesa etch.

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Explanation of anomalously high current gain observed in GaN based bipolar transistors

Cited by 22 publications

References 13 publications

Very high voltage operation (>330 V) with high current gain of AlGaN/GaN HBTs

Very high voltage operation (>330 V) with high current gain of AlGaN/GaN HBTs

Sulfur and low-temperature SiNx passivation of self-aligned graded-base InGaAs/InP heterostructure bipolar transistors

Growth of InGaN HBTs by MOCVD

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