**Experimental and Modeling Study on the High-Performance p**++**-GaAs**/**n**++**-GaAs Tunnel Junctions with Silicon and Tellurium Co-Doped InGaAs Quantum Well Inserted**

**Yudan Gou 1,2, Jun Wang 1,2,\*, Yang Cheng 2, Yintao Guo 2, Xiao Xiao 2, Heng Liu 2, Shaoyang Tan 2, Li Zhou 2, Huomu Yang 1, Guoliang Deng <sup>1</sup> and Shouhuan Zhou <sup>1</sup>**


Received: 26 October 2020; Accepted: 24 November 2020; Published: 28 November 2020

**Abstract:** The development of high-performance tunnel junctions is critical for achieving high efficiency in multi-junction solar cells (MJSC) that can operate at high concentrations. We investigate silicon and tellurium co-doping of InGaAs quantum well inserts in p++-GaAs/n++-GaAs tunnel junctions and report a peak current density as high as 5839 A cm−<sup>2</sup> with a series resistance of 5.86 <sup>×</sup> <sup>10</sup>−<sup>5</sup> <sup>Ω</sup> cm2. In addition, we discuss how device performance is affected by the growth temperature, thickness, and V/III ratio in the InGaAs layer. A simulation model indicates that the contribution of trap-assisted tunneling enhances carrier tunneling.

**Keywords:** tunnel junction; MOCVD; quantum well; co-doping; solar cells
