Improved dc and microwave performance of heterojunction bipolar transistors by full sulfur passivation

Abstract

The temperature-dependent dc characteristics of InGaP∕GaAs heterojunction bipolar transistors with and without full sulfur passivation are systematically studied and demonstrated. The studied device with full sulfur passivation shows lower specific contact resistance ρC, lower sheet resistance Rsh, lower collector-emitter offset voltage ΔVCE, and higher dc gain βF than devices without sulfur passivation. The device with full sulfur passivation also exhibits better rf performance. In addition, the studied device with full sulfur treatment shows lower temperature variation coefficients of ρC,Rsh,ΔVCE, and βF. Thus, the device with sulfur treatment presents relatively temperature-independent characteristics that can extend the transistor action to higher temperature regimes.

Temperature-dependent characteristics of an emitter-ledge passivated InGaP/GaAs heterojunction bipolar transistor

“…Recently, due to their high-speed performance and high-power driving characteristics, InGaP/GaAs heterojunction bipolar transistors (HBTs) have become promising candidates for digital and microwave circuit applications [1][2][3][4]. However, the unpassivated GaAs surface is influenced by the large surface recombination velocity and high surface state density, which limit the scale down and degrade the device performance [5][6][7][8]. In order to overcome these drawbacks, some improved structures have been employed to reduce the surface recombination current, such as emitter ledge structures [5,6], chemical surface passivation [7][8][9] and hydrogen plasma treatment [10].…”

“…However, the unpassivated GaAs surface is influenced by the large surface recombination velocity and high surface state density, which limit the scale down and degrade the device performance [5][6][7][8]. In order to overcome these drawbacks, some improved structures have been employed to reduce the surface recombination current, such as emitter ledge structures [5,6], chemical surface passivation [7][8][9] and hydrogen plasma treatment [10]. Although the chemical surface passivation is a well-known process, its reliability is still a critical factor for practical applications [7][8][9].…”

“…In order to overcome these drawbacks, some improved structures have been employed to reduce the surface recombination current, such as emitter ledge structures [5,6], chemical surface passivation [7][8][9] and hydrogen plasma treatment [10]. Although the chemical surface passivation is a well-known process, its reliability is still a critical factor for practical applications [7][8][9].…”

“…The emitter ledge design is the common approach to reduce the surface recombination and the emitter area effect [5][6][7][8]. Although InGaP/GaAs HBTs with emitter ledge passivation have been widely studied and demonstrated [5,6], little has been published regarding the temperature effect on HBT performance.…”