Near-Infrared Photodetection in n-Type Nanocrystalline FeSi₂/p-Type Si Heterojunctions

Abstract

n-Type nanocrystalline (NC) FeSi2/p-type Si heterojunctions, which were prepared by pulsed laser deposition, were evaluated as a near infrared photodiode. The built-in potential was estimated to be approximately 1.1 eV from the capacitance-voltage measurement. These junctions showed a rectifying behavior accompanied by a large leakage current. The near infrared light detection performance was evaluated using a 1.33 microm laser in the temperature range of 77-300 K. At a reverse bias of -5 V, the detectivity was 5.5 x 10(7) cm Hz1/2 W(-1) at 300 K and it was dramatically enhanced to be 8.0 x 10(10) cm Hz1/2 W(-1) at 77 K. It was demonstrated that NC-FeSi2 is a new potential material applicable to NIR photodetectors operating at low temperatures.

Interface-state density estimation of n-type nanocrystalline FeSi2/p-type Si heterojunctions fabricated by pulsed laser deposition

“…For comparison, the XRD pattern of the NC-FeSi 2 film deposited on a Si(1 1 1) substrate by facing targets direct-current sputtering (FTDCS) was measured in the same manner shown in figure 2. The XRD pattern of the NC-FeSi 2 film deposited by PLD shows a broad peak in the 2θ range between 40 and 50° [14,17], which is similar to that of NC-FeSi 2 film deposited by FTDCS [15]. In this range, orthorhombic β-FeSi 2 has several crystalline planes for diffraction, such as 331, 313, 040, 004, 041, 114, 511, 422, and 133.…”

“…Additionally, β-FeSi 2 grown epitaxially on Si with small lattice mismatches [8][9][10] has an optical absorption coefficient of more than 10 5 cm −1 at 1.2 eV [11][12][13]. Nanocrystalline (NC) FeSi 2 grown on any solid substrate at room temperature possesses semiconducting features close to β-FeSi 2 [14][15][16]. It is comprised of a crystal with diameter range of 3-5 nm [17] and has a larger Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.…”

“…The NC-FeSi 2 thin films possessed n-type conduction and a carrier density ranging between 10 18 to 10 19 cm −3 [17]. After that, the near-infrared (NIR) light detection performance for the n-type NC-FeSi 2 /ptype Si heterojunctions fabricated utilizing PLD was studied [14]. Based on the experimental results, the fabricated heterojunctions demonstrated a large reverse leakage current and a weak NIR light response at room temperature.…”

“…Based on the experimental results, the fabricated heterojunctions demonstrated a large reverse leakage current and a weak NIR light response at room temperature. A probable cause was likely the existing interface states at the heterojunction interface between NC-FeSi 2 and Si acting as a center of leakage current and a trap center for photo-generated carriers [14][15][16]. However, the estimations of the density of interface state (N ss ) and the probable transportation mechanisms of the carrier at the heterojunction interface between NC-FeSi 2 and Si have not been studied in detail yet.…”

The Barrier’s Heights and Its Inhomogeneities on Diamond Silicon Interfaces

“…Figure 4 b clearly shows the existence of two different values of the slopes of the graph vs. 1/2 kT in the range of lower (80–170 K) and higher (170–280 K) temperatures. This may indicate the occurrence of at least two types of interface states in the heterojunction [ 27 ].…”