n‐Doped InGaP Nanowire Shells in GaAs/InGaP Core–Shell p–n Junctions

Liborius, Lisa; Bieniek, Jan; Nägelein, Andreas; Tegude, F.‐J.; Prost, W.; Hannappel, Thomas; Poloczek, A.; Weimann, Nils

doi:10.1002/pssb.201900358

Cited by 3 publications

(15 citation statements)

References 68 publications

(99 reference statements)

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“…Also, for highly doped, coaxial p‐GaAs/n‐InGaP heterojunctions, voltage‐dependent EL spectra at energies well below the GaAs bandgap energy of the junction have been detected previously and were attributed to radiative tunneling processes. [ 29 ] However, due to large (nonradiative) leakage currents an applied forward bias of >2 V was necessary to detect the luminescence and the exact internal voltage drop at the junction was unknown. [ 29 ]…”

Section: Resultsmentioning

confidence: 99%

“…[ 29 ] However, due to large (nonradiative) leakage currents an applied forward bias of >2 V was necessary to detect the luminescence and the exact internal voltage drop at the junction was unknown. [ 29 ]…”

Section: Resultsmentioning

confidence: 99%

“…Diodes from sample I do not exhibit luminescent behavior at low temperatures and applied bias

V

V_{diff}

, similar to observations made on the highly doped junctions. [ 29 ] Figure 5 shows EL spectra of BE diodes from samples II and III with the junctions biased below the expected diffusion voltage

V_{diff}

for all measurements. In Figure 5a, semilogarithmically scaled EL spectra of sample II measured with V = 1.3 V at 79, 120, and 160 K are shown.…”

Section: Resultsmentioning

confidence: 99%

“…The doping concentrations of the different material regions were previously estimated from conductivity measurements on similarly grown structures and amount to 1 × 10 18 cm −3 (SC), 2.5 × 10 18 cm −3 (B), and 3 × 10 18 cm −3 (ECap). [ 28,29 ] The n‐type background doping of the nid‐InGaP is assumed as ≤5 × 10 15 cm −3 , derived from planar nid‐InGaP layers. [ 33 ]…”

Section: Growth and Processingmentioning

confidence: 99%

“…In this study, we focus on the leakage in the forward biased base–emitter (BE) junction, where reverse saturation currents of ≈15 μA cm −2 have been observed. [ 29 ] Electrons tunneling from the emitter into trap states located in the base recombine there, causing an additional BE leakage current. They are lost for the transistor function based on minority carrier electrons crossing the p‐base, limiting the achievable current gain.…”

Section: Introductionmentioning

confidence: 99%

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Tunneling‐Related Leakage Currents in Coaxial GaAs/InGaP Nanowire Heterojunction Bipolar Transistors

Liborius

Bieniek

Possberg

et al. 2020

Physica Status Solidi (b)

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Herein, a detailed analysis of leakage mechanisms in epitaxially grown nanowire heterojunction bipolar transistors (NW‐HBTs) is presented. Coaxial npn‐GaAs/InGaP core–multishell nanowires are grown via gold‐catalyzed metalorganic vapor phase epitaxy, processed to three terminal devices and electrically characterized. The key for successful NW‐HBT device functionality is the identification of tunneling as the dominant leakage mechanism in highly doped nanowire pn‐junctions. The suppression of forward tunneling currents by adjustment of the tunneling barrier width reduces the junction leakage current density into the nA cm−2 regime, which is further verified by tunneling‐related electroluminescence measurements. In addition, the suppressed tunneling accordingly increases the number of electrons that are injected from the n‐emitter into the p‐base. The latter effect influences the performance of pn‐junction based devices and is found to enable bipolar transistor functionality. Measured common emitter Gummel plots of the NW‐HBT exhibit a current gain of up to 9 and the transistor function is additionally verified by current‐controlled output characteristics.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Diodes from sample I do not exhibit luminescent behavior at low temperatures and applied bias

V

V_{diff}

, similar to observations made on the highly doped junctions. [ 29 ] Figure 5 shows EL spectra of BE diodes from samples II and III with the junctions biased below the expected diffusion voltage

V_{diff}

for all measurements. In Figure 5a, semilogarithmically scaled EL spectra of sample II measured with V = 1.3 V at 79, 120, and 160 K are shown.…”

Section: Resultsmentioning

confidence: 99%

Section: Growth and Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tunneling‐Related Leakage Currents in Coaxial GaAs/InGaP Nanowire Heterojunction Bipolar Transistors

Liborius

Bieniek

Possberg

et al. 2020

Physica Status Solidi (b)

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Electrical Properties of the Base‐Substrate Junction in Freestanding Core‐Shell Nanowires

Koch

Liborius

Kleinschmidt

et al. 2022

Adv Materials Inter

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structure through selective adaptation of the material composition, [2] and the possibility of integrating heterocontacts for tunnel junctions, [3] charge-selective contacts, [4] or tunnel barriers, [5,6] a multitude of applications can be targeted. In order to realize these types of device components, special attention must be paid to their surfaces and interfaces, since their electrical properties can be strongly influenced by surface termination and the sequence of layer deposition, especially in the case of core-shell structures. [7] In this context, various groups have developed and investigated epitaxially grown ternary III-V NWs, in particular with III-III-V compositions, such as axial NWs comprising AlGaAs, [8] AlGaP, [9] InGaAs, [10] or radial NWs utilizing AlGaAs. [11][12][13][14][15] III-V based core-shell NWs incorporating p-n or p-i-n junctions have enabled device designs with improved properties, leading to an increase in quantum efficiency and a reduction of non-radiative recombination losses (which in turn increases the effective minority charge carrier lifetimes). This results in improved optoelectronic performance, e.g., enhanced photoluminescence emission. [16] However, these vapor liquid solid (VLS)-grown, multinary III-III-V NWs may exhibit heterogeneous compositions along the NWs as well as in radial direction, caused, e.g., by spontaneous elemental segregation, carry-over effects, or growth Well-defined hetero-interfaces with controlled properties are crucial for any highperformance, semiconductor-based, (opto-)electronic device. They are particularly important for device structures on the nanoscale with increased interfacial areas. Utilizing a ultrahigh-vacuum based multi-tip scanning tunneling microscope, this work reveals inadvertent conductivity channels between the nanowire (NW) base and the substrate, when measuring individual vertical core-shell III-V-semiconductor NWs. For that, four-terminal probing is applied on freestanding, epitaxially grown coaxial p-GaAs/i-GaInP/n-GaInP NWs without the need of nanoscale lithography or deposition of electrical contacts. This advanced analysis, carried out after composition-selective wet chemical etching, reveals a substantially degraded electrical performance of the freestanding NWs compared to detached ones. In an electron beam induced current mode of the nanosensor, charge separation at the substrate-to-NW base junction is demonstrated. An energy dispersive X-ray spectroscopic linescan shows an unintended compositional change of the epitaxially grown NW toward the planar layers caused by different incorporation mechanisms of Ga and In at the NW base. This approach provides direct insight into the NW-substrate transition area and leads to a model of the conductivity channels at the NW base, which should, in principle, be considered in the fabrication of all NW heterostructures grown bottom-up on heterogeneous substrate materials.

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Impact of the Tip-to-Semiconductor Contact in the Electrical Characterization of Nanowires

Koch,

Liborius,

Kleinschmidt

et al. 2024

ACS Omega

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Well-defined semiconductor heterostructures are a basic requirement for the development of high-performance optoelectronic devices. In order to achieve the desired properties, a thorough study of the electrical behavior with a suitable spatial resolution is essential. For this, various sophisticated tip-based methods can be employed, such as conductive atomic force microscopy or multitip scanning tunneling microscopy (MT-STM). We demonstrate that in any tip-based measurement method, the tip-to-semiconductor contact is decisive for reliable and precise measurements and in interpreting the properties of the sample. For that, we used our ultrahigh-vacuum-based MT-STM coupled in vacuo to a reactor for the preparation of nanowires (NWs) with metal organic vapor phase epitaxy, and operated our MT-STM as a four-point nanoprober on III−V semiconductor NW heterostructures. We investigated a variety of upright, free-standing NWs with axial as well as coaxial heterostructures on the growth substrates. Our investigation reveals charging currents at the interface between the measuring tip and the semiconductor via native insulating oxide layers, which act as a metal− insulator−semiconductor capacitor with charging and discharging conditions in the operating voltage range. We analyze in detail the observed I−V characteristics and propose a strategy to achieve an optimized tip-to-semiconductor junction, which includes the influence of the native oxide layer on the overall electrical measurements. Our advanced experimental procedure enables a direct relation between the tip-to-NW junction and the electronic properties of as-grown (co)axial NWs providing precise guidance for all future tip-based investigations.

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n‐Doped InGaP Nanowire Shells in GaAs/InGaP Core–Shell p–n Junctions

Cited by 3 publications

References 68 publications

Tunneling‐Related Leakage Currents in Coaxial GaAs/InGaP Nanowire Heterojunction Bipolar Transistors

Tunneling‐Related Leakage Currents in Coaxial GaAs/InGaP Nanowire Heterojunction Bipolar Transistors

Electrical Properties of the Base‐Substrate Junction in Freestanding Core‐Shell Nanowires

Impact of the Tip-to-Semiconductor Contact in the Electrical Characterization of Nanowires

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