Electrical and optical properties of InP nanowire ensemble p⁺–i–n⁺photodetectors

Abstract

We report on a comprehensive study of electrical and optical properties of efficient near-infrared p⁺-i-n⁺ photodetectors based on large ensembles of self-assembled, vertically aligned i-n⁺ InP nanowires monolithically grown on a common p⁺ InP substrate without any buffer layer. The nanowires have a polytype modulated crystal structure of wurtzite and zinc blende. The electrical data display excellent rectifying behavior with an ideality factor of about 2.5 at 300 K. The ideality factor scales with 1/T, which possibly reflects deviations from classical transport models due to the mixed crystal phase of the nanowires. The observed dark leakage current is of the order of merely ∼100 fA/nanowire at 1 V reverse bias. The detectors display a linear increase of the photocurrent with reverse bias up to about 10 pA/nanowire at 5 V. From spectrally resolved measurements, we conclude that the photocurrent is primarily generated by funneling photogenerated carriers from the substrate into the NWs. Contributions from direct excitation of the NWs become increasingly important at low temperatures. The photocurrent decreases with temperature with an activation energy of about 50 meV, which we discuss in terms of a temperature-dependent diffusion length in the substrate and perturbed transport through the mixed-phase nanowires.

First-principles study of the phonon dispersion and dielectric properties of wurtzite InP: Role of In4delectrons

“…Self-assembled nanowires based on III-V materials like InP have shown great promise for a range of applications including field effect transistors [1], photodetectors [2], thermoelectrics [3], and solar cell arrays [4]. This is due in large part to a number of superlative attributes of these systems, including direct band gaps, high mobility electrons, and the ability to selectively dope regions n or p type.…”

Crystal facet effect on structural stability and electronic properties of wurtzite InP nanowires

“…[1][2][3] This stems in part from their one-dimensional structural characteristic which allows to engineer the electronic band structure and overcomes the lattice mismatch between NWs and Si substrate for the compatibility with Si technology. 4,5 Many applications of III-V NWs to nanoscale devices have been demonstrated, such as field-effect transistors, 6 light emitting diodes, 7 single-photon sources, 8 sensors, photodetectors, 9 and solar cells. 10 Among III-V NWs, InP NWs are one of most studied targets due to their successful realization of both n-and p-type doping, 11 which makes them a promising candidate material for nextgeneration electronic and optoelectronic devices.…”

Optical phonon modes of wurtzite InP

“…As a consequence, they have been employed in optical device applications, as well as for fundamental physics investigation. [1][2][3][4][5][6] In general, bulk III-V compounds can crystallize in both hexagonal and cubic crystal structures, depending on the specific elements involved. In particular, phosphide and arsenide III-V compounds typically grow in the cubic phase, which for these materials is the most stable at ambient pressure.…”