Passivation of InGaAs surfaces and InGaAs/InP heterojunction bipolar transistors by sulfur treatment

Abstract

The surface properties of InGaAs(100) after ex situ treatment with (NH4)2S solution were investigated by photoluminescence (PL) and high-energy resolution x-ray photoelectron spectroscopy. The As 3d, Ga 2p3/2, and In 3d5/2 core level studies show that the surface is free of native oxides and is terminated by S after treatment. A dramatic increase (∼40 times) in the PL efficiency was observed on undoped InGaAs(100) surfaces after sulfur passivation. This S treatment has also been applied to the passivation of the extrinsic base of InGaAs/InP heterojunction bipolar transistors (HBTs). The effectiveness of the sulfur passivation treatment was confirmed by the resulting devices which exhibited dc current gain values of up to 200 at very low collector currents (nA). Further, the sulfur passivated HBTs do not show any dependence on the perimeter-to-area (P/A) ratio of the emitter junction which is of interest for high frequency characteristics while maintaining high current gain.

Hafnium oxide passivation of InGaAs/InP heterostructure bipolar transistors by electron beam evaporation

“…Moreover, the XRR fitted dielectric total thickness of ~ 13 nm is quite similar to the value previously measured by ellipsometry. Furthermore, the calculated film density of 10.3 g/cm 3 for HfO 2 film is in agreement with values reported in literature [13,[21][22][23]. The effects of the HfO 2 passivation are shown by comparing the electrical characteristics of large area InGaAs/InP HBTs before and after e-beam evaporation.…”

“…There is a great amount of literature data reporting significant reduction of the surface recombination velocity and enhancement of the photoluminescence intensity on III-V surfaces after wet or dry chemical treatments [3,4]. However, the effects of passivation treatments have been shown to be strongly dependent on the device layer structures and process parameters.…”

“…3). In order to improve the quality of the fit, the model was refined by adding a thin layer (~ 1.3 nm, with a density of 3.1 g/cm 3 ) at the dielectric-semiconductor interface. As can be seen from Fig.…”

Silicon nitride and polyimide capping layers on InGaAs/InP PIN photodetector after sulfur treatment

“…6, the dark current characteristics of the devices after removing silicon nitride are nearly the same as before depositing the silicon nitride. A clear recovery of the detector dark current after removing the silicon nitridecapping layer indicates that the degradation process is reversible, and the initial characteristics can be almost totally restored after dielectric film removal by HF etching as also reported earlier [15].…”

Improved InP‐based double heterojunction bipolar transistors

“…One has an abrupt B-C heterojunction (denoted as abrupt DHBT) and the other has a composite collector design (denoted as composite DHBT). Furthermore, numerous stud-ies have established the benefits of passivation in HBTs [3,17,[18][19][20]. Reported passivation processes involve chemical passivation [17,18], dielectric passivation [19,20] and ledge passivation [3].…”