High-Performance AlGaN Heterojunction Phototransistor With Dopant-Free Polarization-Doped P-Base
Lijie Sun, Zesheng Lv, Zhenhua Zhang, Xinjia Qiu, Hao Jiang
Abstract
A dopant-free p-type Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> N (x = 0.1~0) layer, achieved by polarization induced three-dimensional hole gas, was introduced into the structure of AlGaN npn heterojunction phototransistors (HPTs) as the p-base. The fabricated HPTs with a junction diameter of 150 μm exhibit a sharp cutoff with a 360/375-nm rejection ratio of more than 3 orders of magnitude and a responsivity of 5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> A/W at 360 nm under the 2 V collector bias. A high optical gain of 6.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> was obtained at 10 V bias. These results demonstrate the feasibility of polarization-doped p-base in developing high-performance AlGaN UV HPTs.