Determination of bandgap narrowing and parasitic energy barriers in SiGe HBT's integrated in a bipolar technology

Abstract

Abstract-This paper describes a method for characterizing the bandgap narrowing and parasitic energy barrier in SiGe heterojunction bipolar transistors (HBT's), fabricated using a singlepolysilicon self-aligned bipolar process. From a comprehensive study of the temperature dependence of the collector current, the bandgap narrowing in the base due to germanium has been dissociated from that due to the heavy dopant concentration. The same approach has been used to characterize the height and width of parasitic energy barriers which appear when boron out-diffusion from the SiGe base is present. The method has been applied to SiGe heterojunction bipolar transistors fabricated using a single polysilicon, self aligned, bipolar process, as well as mesa transistors. The experimental results show that small geometry transistors have degraded collector currents due to boron out-diffusion around the perimeter of the emitter. This behavior has been explained by accelerated boron diffusion due to point defect generated during the extrinsic base implant. The values of undoped SiGe spacer thickness needed to suppress the parasitic energy barrier are described. Finally, high-frequency results are reported, which correlate the frequency transition to these parasitic energy barriers.

Source/drain induced defects in advanced MOSFETs: what device electrical characterization tells

“…Article presence of which is easily identified at low temperature [6]. It has been verified experimentally that extrinsic base implantations were responsible for a broadening of the intrinsic base at the periphery of the device [7,8].…”

Heterodielectric oxide‐engineered single‐lateral pocket‐based gated source TFET

“…Furthermore, Schenk Trap Assisted Tunneling and Shockley‐Read‐Hall recombination models are used to capture defect assisted leakage and the impact of carrier lifetimes 29 . High source doping induced band shrinking effects are captured using the OldSlotBoom bandgap narrowing model 30 . At A path = 1.70 × 10 15 cm −3 s −1 , B path = 1.6 × 10 7 V cm −1 for silicon, and A path = 2.27 × 10 15 cm −3 s −1 , B path = 1.55 × 10 7 V cm −1 for the Si 0.55 Ge 0.45 body, the simulated curve matches quite well with experimental results for V DS = 1.2 V, as shown in Figure 1E.…”

Penurunan Noise Figure Performance (Fn) Pada HBT Si / Si 1-X Gex Berdasarkan Pengaturan Stripe Emiter Area (Ae) Dan Fraction Mole (X).

“…Dengan memperhitungkan pengaruh rekombinasi, densitas arus kolektor (J C ) dapat dinyatakan dengan Persamaan 4,5 dan 6. D nB adalah konstanta difusi elektron pada basis untuk basis pendek (short base) dengan doping merata, [11] [12] , Besarnya densitas arus kolektor pada HBT SiGe dipengaruhi oleh energi bandgap total (ΔE g ) , sehingga current gain (β) dinyatakan Persamaan 6. [13]:…”