Formation of van der Waals Stacked p–n Homojunction Optoelectronic Device of Multilayered ReSe₂ by Cr Doping

Abstract

of device junctions such as metal oxide semiconductor (MOS) p-and n-channel, tunneling p-or n-junction, and Schottky junction, etc., can be crafted and fabricated separately. In the post-silicon era, newgeneration van der Waals materials such as two-dimensional (2D) semiconductors have received extensive attention and research due to their practical advantages of smooth surface, [1,2] high mobility, [3] ultrathin, [4] flexibility, [5,6] in-plane structural and optical anisotropy, [7][8][9][10] thickness-dependent carrier conduction, [11] thickness tunable bandgap, [12,13] and abundance of direct band-edge excitons. [14,15] Among them, transition metal dichalcogenides (TMDs), including four popular members, MoS 2 , MoSe 2 , WS 2 , and WSe 2 , have been vigorously studied and have potential capabilities in practical semiconductor device applications such as field-effect transistors, [16] bipolar junction transistors, [17,18] phototransistors, [19] and light-emitting diodes (LEDs), [20] etc., due to their high environmental stability and the flexibility on thickness tuning bandgaps. The growth of p-and n-type materials in TMDs layers may be a key issue for the development of various p-n junction devices in 2D semiconductor technology. However, to date, the synthesis of p-type layered TMDs is still challenging, and even some proposals have been made related to Nbdoped p-MoSe 2 , [21] Nb-doped p-MoS 2 , [22] oxygen plasma doped p-MoS 2 , [23] and nitrogen-induced p-WS 2 , [24] etc., the information on the ideal dopants for forming p-type TMDs with controllable carrier concentration and good stability is still insufficient and needs to be further explored. Nowadays, many TMD bipolar p-n junction devices and LEDs typically operate in gate-controlled p-and n-type with a lateral junction, [20,25,26] and a large number of vertically stacked 2D layered devices are still fabricated as heterostructures and heterojunctions [17,18] because of the lack of van der Waals stacked p-n homojunction.Compared to conventional MoS 2 , MoSe 2 , WS 2 , and WSe 2 dichalcogenides, rhenium diselenide (ReSe 2 ) is also an important member of the TMD-family 2D semiconductors, which crystallizes in a specific distorted CdI 2 -type layered structure of triclinic symmetry (space group P1). [27,28] Dissimilar to that the MoS 2 group has a uniform and isotropic layer plane in generally two-layer hexagonal or three-layer rhombohedral form, the structural distortion in the CdI 2 -type (i.e., 1T′) ReSe 2 layer may cause by a specific d 3 nonbonding Re-Re interaction and which The formation of p-or n-type material via impurity doping should be crucial and essentially prior to the establishment of junction devices in semiconductor processing. Especially in a 2D transition-metal dichalcogenide (TMD), dopant selection for growing p-and n-type TMD semiconductors may suffer much higher difficulty and complexity than conventional Si and III-V compounds owing to the complicated valences occurred in transition metals. Different amount of chromium doped in ReSe ...

Phosphorus-Doped Multilayer In6Se7: The Study of Structural, Electrical, and Optical Properties for Junction Device

“…The other doped 2D materials like Cr-doped ReS 2 and Cr-doped ReSe 2 also showed identical structures and unchanged lattice parameters with altered dopant content in the crystals. The Cr in ReSe 2 may act as an impurity dopant for changing the carrier concentration of the layer semiconductor . Thus, different P-doped compositions in In 6 Se 7 may also be inferred to have an effect on modulation of the carrier density of the layer compounds.…”

“…The plots of lattice constants that are determined by XRD and TEM results are comparable and presented in Figure 1 d. The obtained lattice constants are a = 9.433 ± 0.06 Å, b = 4.068 ± 0.05 Å, c = 18.378 ± 0.05 Å, and β = 109.29° ± 0.05°, respectively. The other doped 2D materials like Cr-doped ReS 2 52 and Cr-doped ReSe 2 53 also showed identical structures and unchanged lattice parameters with altered dopant content in the crystals. The Cr in ReSe 2 may act as an impurity dopant for changing the carrier concentration of the layer semiconductor.…”

Polarization-Sensitive Self-Powered Schottky Photodetector with High Photovoltaic Performance Induced by Geometry-Asymmetric Contacts

“…Other samples will be discussed later. Figure 1c displays the normalized Raman spectrum of the ReSe 2 nanosheet in 35 Figure 1d shows the corresponding I ds −V ds curve for device#1 in both linear and logarithmic scales in darkness. It exhibits a photodiode behavior with a forward rectification ratio of 29, implying the difference in the Schottky barrier height between regions A and B.…”

“…Eighteen Raman vibration peaks for ReSe 2 can be classified into three categories. − The peaks located at 104.3, 117.1, 118.4, and 284.1 cm –1 belong to the out-of-plane A g -like mode, while the other Raman peaks that appear at 124.8, 161.7, 173.2, and 190.9 cm –1 belong to the in-plane E g mode. The C p (coupled in-plane and out-of-plane) vibration modes correspond to the peaks at 180.8, 217.5, 231.4, 246.5, and 260.3 cm –1 . − Furthermore, most vibration modes appearing below 200 cm –1 are mainly responsible for the low lattice symmetry and the heavier Re involved in the lattice structure …”

Contemporary innovations in two-dimensional transition metal dichalcogenide-based P–N junctions for optoelectronics

“…In other words, the junction is made up of the same kind of 2D materials on both sides but with varying degrees of doping, as shown in Fig. 1(a). 95–97 The movement of charge carriers (electrons and holes) through the junction is governed by the potential barrier that is created at the junction owing to the difference in doping levels. A heterojunction p–n is a form of interface in which the p-region and n-region are constructed of separate 2D materials, as shown in Fig.…”