Dataset Information

A New Analytic Formula for Minority Carrier Decay Length Extraction from Scanning Photocurrent Profiles in Ohmic-Contact Nanowire Devices.

ABSTRACT: Spatially resolved current measurements such as scanning photocurrent microscopy (SPCM) have been extensively applied to investigate carrier transport properties in semiconductor nanowires. A traditional simple-exponential-decay formula based on the assumption of carrier diffusion dominance in the scanning photocurrent profiles can be applied for carrier diffusion length extraction using SPCM in Schottky-contact-based or p-n junction-based devices where large built-in electric fields exist. However, it is also important to study the electric-field dependent transport properties in widely used ohmic-contact nanowire devices where the assumption of carrier diffusion dominance is invalid. Here we derive an analytic formula for scanning photocurrent profiles in such ohmic-contact nanowire devices under uniform applied electric fields and weak optical excitation. Under these operation conditions and the influence of photo-carrier-induced electric field, the scanning photocurrent profile and the carrier spatial distribution strikingly do not share the same functional form. Instead, a surprising new analytic relation between the scanning photocurrent profile and the minority carrier decay length was established. Then the derived analytic formula was validated numerically and experimentally. This analytic formula provides a new fitting method for SPCM profiles to correctly determine the minority carrier decay length, which allows us to quantitatively evaluate the performance of nanowire-based devices.

SUBMITTER: Chu CH

PROVIDER: S-EPMC6603194 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A New Analytic Formula for Minority Carrier Decay Length Extraction from Scanning Photocurrent Profiles in Ohmic-Contact Nanowire Devices.

Chu Cheng-Hao CH Mao Ming-Hua MH Yang Che-Wei CW Lin Hao-Hsiung HH

Scientific reports 20190701 1

Spatially resolved current measurements such as scanning photocurrent microscopy (SPCM) have been extensively applied to investigate carrier transport properties in semiconductor nanowires. A traditional simple-exponential-decay formula based on the assumption of carrier diffusion dominance in the scanning photocurrent profiles can be applied for carrier diffusion length extraction using SPCM in Schottky-contact-based or p-n junction-based devices where large built-in electric fields exist. Howe ...[more]

PMID: 31263209

Similar Datasets

Project description:Carrier transport was studied both numerically and experimentally using scanning photocurrent microscopy (SPCM) in two-dimensional (2D) transport structures, where the structure size in the third dimension is much smaller than the diffusion length and electrodes cover the whole terminal on both sides. Originally, one would expect that with increasing width in 2D transport structures, scanning photocurrent profiles will gradually deviate from those of the ideal one-dimensional (1D) transport structure. However, the scanning photocurrent simulation results surprisingly showed almost identical profiles from structures with different widths. In order to clarify this phenomenon, we observed the spatial distribution of carriers. The simulation results indicate that the integrated carrier distribution in the 2D transport structures with finite width can be well described by a simple-exponential-decay function with the carrier decay length as the fitting parameter, just like in the 1D transport structures. For ohmic-contact 2D transport structures, the feasibility of the fitting formula from our previous 1D analytical model was confirmed. On the other hand, the application of a simple-exponential-decay function in scanning photocurrent profiles for the diffusion length extraction in Schottky-contact 2D transport structures was also justified. Furthermore, our simulation results demonstrate that the scanning photocurrent profiles in the ohmic- or Schottky-contact three-dimensional (3D) transport structures with electrodes covering the whole terminal on both sides will reduce to those described by the corresponding 1D fitting formulae. Finally, experimental SPCM on a p-type InGaAs air-bridge two-terminal thin-film device was carried out. The measured photocurrent profiles can be well fitted by the specific fitting formula derived from our previous 1D analytical model and the extracted electron mobility-lifetime product of this thin-film device is 6.6 × 10-7 cm2·V-1. This study allows us to extract the minority carrier decay length and to obtain the mobility-lifetime product which can be used to evaluate the performance of 2D carrier transport devices.

Dataset Information

A New Analytic Formula for Minority Carrier Decay Length Extraction from Scanning Photocurrent Profiles in Ohmic-Contact Nanowire Devices.

Publications

A New Analytic Formula for Minority Carrier Decay Length Extraction from Scanning Photocurrent Profiles in Ohmic-Contact Nanowire Devices.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure