Recent Advances on Pulsed Laser Deposition of Large-Scale Thin Films.

2D thin films, possessing atomically thin thickness, are emerging as promising candidates for next-generation electronic devices, due to their novel properties and high performance. In the early years, a wide variety of 2D materials are prepared using several methods (mechanical/liquid exfoliation, chemical vapor deposition, etc.). However, the limited size of 2D flakes hinders their fundamental research and device applications, and hence the effective large-scale preparation of 2D films is still challenging. Recently, pulsed laser deposition (PLD) has appeared to be an impactful method for wafer-scale growth of 2D films, owing to target-maintained stoichiometry, high growth rate, and efficiency. In this review, the recent advances on the PLD preparation of 2D films are summarized, including the growth mechanisms, strategies, and materials classification. First, efficacious strategies of PLD growth are highlighted. Then, the growth, characterization, and device applications of various 2D films are presented, such as graphene, h-BN, MoS2 , BP, oxide, perovskite, semi-metal, etc. Finally, the potential challenges and further research directions of PLD technique is envisioned.

Non-volatile optoelectronic memory based on a photosensitive dielectric.

Recently, the optoelectronic memory is capturing growing attention due to its integrated function of sense and memory as well as multilevel storage ability. Although tens of states have been reported in literature, there are still three obvious deficiencies in most of the optoelectronic memories: large programming voltage (>20 V), high optical power density (>1 mW cm-2), and poor compatibility originating from the over-reliance on channel materials. Here, we firstly propose an optoelectronic memory based on a new photosensitive dielectric (PSD) architecture. Data writing and erasing are realized by using an optical pulse to switch on the PSD. The unique design enables the memory to work with a programming voltage and optical power density as low as 4 V and 160 µW cm-2, respectively. Meanwhile, this device may be extended to different kinds of transistors for specific applications. Our discovery offers a brand-new direction for non-volatile optoelectronic memories with low energy consumption.

High Dielectric Transparent Film Tailored by Acceptor and Donor Codoping.

High dielectric constant materials are of particular current interests as indispensable components in transistors, capacitors, etc. In this context, there are emerging trends to exploit defect engineering in dielectric ceramics for enhancing the performance. However, demonstrations of similar high dielectric performance in integration-compatible crystalline films are rare. Herein, such a breakthrough via the functionalization of donor-acceptor dipoles by compositional tuning in GaCu codoped ZnO films is reported. The dielectric constant reaches ~200 at 1 kHz and the optical transmittance in visible light reaches ~80%. Importantly, by analyzing the impedance spectroscopy data, prominent relaxation mechanisms in correlation with the dipole properties, enabling consistent explanations of the dielectric constant as a function of frequency are discriminated. The atomistic nature of the dipoles is revealed by the systematic X-ray spectroscopy analysis. Spectacularly, similar trends for the dielectric properties are observed, while synthesizing samples by pulsed laser deposition and ion implantation, indicating the general character of the phenomena.

Higher-Order Multiphoton Absorption Upconversion Lasing Based on ZnO/ZnMgO Multiple Quantum Wells.

In the progress of nonlinear optics, multiphoton absorption (MPA) upconversion lasing enables many vital applications in bioimaging, three-dimensional optical data storage, and photodynamic therapy. Here, efficient four-photon absorption upconversion lasing from the ZnO/ZnMgO multiple quantum wells (MQWs) at room temperature is realized. Moreover, the MPA upconversion lasing and third-harmonic generation peak generated in the MQWs under the excitation of a femtosecond (fs) laser pulse were observed concurrently, and the essential differences between each other were studied comprehensively. Compared with the ZnO film, the upconversion lasing peak of the ZnO/ZnMgO MQWs exhibits a clear blue shift. In addition, the four-photon absorption upconversion photoluminescence (PL) intensity was enhanced in the MQWs/Au nanoparticles (NPs) by the metal-localized surface plasmons (LSPs). The work paves the way for short-wavelength lasers by taking advantage of the high stability and large exciton binding energy of the MQWs' structures.

Robust hetero-MoO3/MoO2@N-doped carbon nanobelts decorated with oxygen deficiencies as high-performance anodes for potassium/sodium storage.

Hetero-MoO3/MoO2@N-doped carbon nanobelt anodes (h-MoO3/MoO2@NC) with long lifespan and superior rate capability were proposed by a simple in situ reduction tactic, in which pristine MoO3 was transformed into heterogeneous MoO3/MoO2. The hetero-MoO3/MoO2 architecture significantly improves the electronic conductivity and affords abundant oxygen deficiencies. Meanwhile, the synergistic effect of internal MoO3/MoO2 heterostructure and outer N-doped carbon layer (NC) accomplishes a balance of sustainable potassium/sodium storage and ultra-durable structure stability. In potassium ion batteries, the anodes steadily maintain a reversible capacity of 283 mAh g-1 after 6000 cycles at 0.5 A g-1 and 153 mAh g-1 after 1000 cycles under 2 A g-1, as well as an impressive rate capability of 131 mAh g-1 at 3 A g-1. In sodium ion batteries, the anodes purchase a steady capacity of 152 mAh g-1 even after 10,000 cycles at 2 A g-1, and 190 mAh g-1 after 5000 cycles at 0.5 A g-1. Moreover, the h-MoO3/MoO2@NC composite possesses a prominent pseudocapacitive effect and good thermal adaptability (-10 to 50 °C) in both KIBs and SIBs. The results indicate that the h-MoO3/MoO2@NC composite would be an auspicious material for potassium/sodium storage and other ion batteries.

Shape-control growth of 2D-In2Se3 with out-of-plane ferroelectricity by chemical vapor deposition.

For potential applications in ferroelectric switching and piezoelectric nano-generator devices, the promising ferroelectric properties of two dimensional (2D) layered In2Se3 attracted much attention. In the present study, 2D In2Se3 flakes down to monolayers are grown by the chemical vapor deposition (CVD) technique on a mica substrate with their structural, optical and ferroelectric properties being studied. The effect of growth parameters (time of growth and Ar flow rate) on the shape and size of the deposited flakes was studied. The optical microscopy study revealed that the flake changed from a circular shape to a sharp face triangle as the Ar flow rate and growth time increased. Raman spectroscopy and high-resolution scanning transmission electron microscopy (HR-STEM) studies revealed that the flakes were of α and ß phases, each of which has a hexagonal crystal structure. Strong second harmonic generation (SHG) was observed from α-In2Se3, demonstrating its non-centrosymmetric structure. The piezo-force microscopic (PFM) study showed the presence of out of plane (OOP) ferroelectricity with no in plane (IP) ferroelectricity in CVD grown α-In2Se3 indicating its vertically confined piezoresponse, which was tuned by the applied electric bias and the flake thickness. The present result of shape-controlled growth of In2Se3 with OOP ferroelectricity would open new pathways in the field of 2D ferroelectric switching devices.

Challenges, Learning Curve, and Safety of Endoscopic Endonasal Surgery of Sellar-Suprasellar Lesions in a Community Hospital.

BACKGROUND AND OBJECTIVE: Endoscopic endonasal surgery (EES) for the management of sellar, suprasellar, and anterior skull base lesions is gaining popularity. Our aim was to analyze and present the clinical outcomes of EES for the management of these lesions in a community hospital setting. METHODS: We retrospectively reviewed the charts of 56 patients with sellar, suprasellar, and anterior skull base lesions who underwent EES between 2010 and 2018. RESULTS: There was male predominance (53.6%) with a mean age of 54.9 ± 13.7 years. Lesions were 45 pituitary adenomas, 5 meningiomas, 3 metastatic, 1 craniopharyngioma, 1 Rathke cyst, and 1 mucocele. Gross total excision was achieved in 57.1%, subtotal excision occurred in 37.5%, and decompression and biopsy were achieved in 5.4% patients. Postoperative vision normalized or improved in 27 patients (86.1%) and was stable in 4 patients (13.9%). Recovery of a preexisting hormonal deficit occurred in 13 (23.2%) patients, and a new hormonal deficit occurred in 9 patients (16.1%). The mean hospital stay was 6.1 ± 4.9 days. Postoperative complications included cerebrospinal fluid leak in 8 patients (14.3%). Four patients (7.1%) had meningitis. Diabetes insipidus was present in 19 patients (33.9%), and postoperative intracranial hematoma requiring evacuation was necessary in 2 patients (3.6%). The mean follow-up duration was 47.5 ± 25.8 months. Lesion progression or recurrence requiring redo surgery occurred in 5 patients (8.9%). Regarding the learning curve, the postoperative cerebrospinal fluid leak, meningitis, new hormonal deficits, and diabetes insipidus decreased in the second half of the patients. CONCLUSIONS: EES provides an effective and safe surgical option with low morbidity and mortality for the treatment of sellar, suprasellar, and anterior skull base lesions in a community hospital setting.

Vacancy cluster in ZnO films grown by pulsed laser deposition.

Undoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant VZn-related defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O2) is a vacancy cluster (most likely a VZn-nVO complex with n = 2, 3) rather than the isolated VZn which has a lower formation energy. Annealing these samples at 900 °C induces out-diffusion of Zn from the ZnO film into the sapphire creating the VZn at the film/sapphire interface, which favors the formation of vacancy cluster containing relatively more VZn. Increasing the P(O2) during growth also lead to the formation of the vacancy cluster with relatively more VZn. For Ga-doped ZnO films, the oxygen pressure during growth has significant influence on the electron concentration and the microstructure of the VZn-related defect. Green luminescence (GL) and yellow luminescence (YL) were identified in the cathodoluminescence study (CL) study, and both emission bands were quenched after hydrogen plasma treatment. The origin of the GL is discussed.

Reversible Tuning of Ferromagnetism and Resistive Switching in ZnO/Cu Thin Films.

Systematic magnetic, electronic, and electrical studies on the Cu0.04Zn0.96O/Ga0.01Zn0.99O cell structure grown on (001) sapphire by the pulsed laser deposition technique show that the Cu multivalent (CuM+) ions modulate magnetic and resistive states of the cells. The magnetic moment is found to be reduced by ∼30% during the high resistance state (HRS) to low resistance state (LRS) switching. X-ray photoelectron spectroscopy results reveals an increase of the Cu+/Cu2+ oxidation state ratio (which has been determined by the relative positions of the Fermi level and the Cu acceptor level) during the HRS to LRS transition. This decreases the effective spin-polarized Cu2+-Vö-Cu+ channels and thus the magnetic moment. A conduction mechanism involving the formation of conductive filaments from the coupling of the CuM+ ions and Vö has been suggested.

p-type doping of MgZnO films and their applications in optoelectronic devices.

A lithium and nitrogen codoping method has been employed to prepare p-type MgZnO films, and p-MgZnO/i-ZnO/n-ZnO structured light-emitting devices (LEDs) and photodetectors have been fabricated. The LEDs can work continuously for about 97 h under the injection of a 20 mA continuous current, which is the best value ever reported for ZnO-based LEDs. The performance of the photodetectors degrades little after several running cycles. The above results reveal the applicability of the p-MgZnO films in optoelectronic devices.

Radiology and endoscopic findings of silent maxillary sinus atelectasis and enophthalmos.

OBJECTIVES: The objective of this study is to discuss the presentation and surgical management of patients presenting with silent maxillary sinus atelectasis with enophthalmos (SMSAE). STUDY DESIGN AND METHODS: We performed an analysis of prospectively collected data on patients with maxillary sinus opacification and associated enophthalmos from 1999 to 2003. Patients were evaluated based on physical examination, nasal endoscopy, and computed tomographic findings. RESULTS: Sixty-four patients were identified with unilateral maxillary sinus opacification. Of these, 7had radiographic evidence of maxillary sinus volume reduction. Of these 7 patients, 5 had maxillary sinus atelectasis with enophthalmos, the components constituting SMSAE. The mean age of the patients was 42 years (range, 22-65). None of the patients had any history of nasal trauma or developmental defects before presentation. All 5 patients with SMSAE had uncinate retraction on nasal endoscopy. Uncinate retraction was not seen in the 2 patients without enophthalmos (chi(2) = 7, P= .008). All 7 patients with maxillary opacification were treated with endoscopic sinus surgery, with resolution of their maxillary sinus obstruction at 2 years' follow-up. Only 1 of 5 patients with SMSAE requested orbital floor reconstruction after sinus surgery performed by the oculoplastic service with resolution of enophthalmos. CONCLUSION: All patients with SMSAE had evidence of uncinate process retraction on nasal endoscopy, whereas patients without enophthalmos did not, and the difference was statistically significant. Surgical treatment is the mainstay of therapy for this condition, with resolution of maxillary opacification at 2 years' follow-up.

Rhinosinusitis Task Force symptoms versus the Sinonasal Outcomes Test in patients evaluated for chronic rhinosinusitis.

BACKGROUND: The aim of this study was to compare Rhinosinusitis Task Force (RSTF) symptom scores with Sinonasal Outcome Test 20 (SNOT-20) in patients with chronic rhinosinusitis (CRS) and controls. METHODS: An analysis was performed of prospectively collected data in patients with CRS (n=201) and controls (n=100). The severity of individual RSTF major and minor symptom scores graded on a visual analog scale and total symptom scores were compared between the two groups. Correlation of the RSTF symptoms with the SNOT-20 was performed using data collected from the CRS group at baseline and at 1 year postoperatively. RESULTS: CRS patients had higher RSTF symptom scores compared with control patients when asked to rate the severity of nasal obstruction, facial pain/pressure, facial congestion, alteration of smell, nasal discharge, postnasal drip, headache, halitosis, fatigue, cough, and ear pain (p < 0.005). No statistically significant difference was seen for the symptoms of dental pain and fever. Total RSTF scores were 54.5 +/- 1.9 in CRS patients versus 23.4 +/- 3.0 in controls. Total SNOT-20 scores were 28.7 +/- 0.8 in CRS patients versus 15.2 +/- 0.6 in controls. In CRS patients, total RSTF scores correlated with total SNOT-20 scores at baseline (r = 0.36; p < 0.0001) and 1-year postoperatively (r = 0.37; p < 0.0001). CONCLUSION: Total RSTF symptom scores are significantly different in patients with chronic rhinosinusitis compared with those without this disease. The total RSTF symptom scores also correlate with a validated outcome measures instrument.

Important clinical symptoms in patients undergoing functional endoscopic sinus surgery for chronic rhinosinusitis.

OBJECTIVE: To evaluate the prevalence and severity of individual Rhinosinusitis Task Force (RSTF) symptoms in patients with chronic rhinosinusitis (CRS) undergoing functional endoscopic sinus surgery (FESS). METHODS: Retrospective analysis of prospectively collected data in 201 patients treated with FESS. The prevalence and severity of individual RSTF major and minor symptom scores graded on a visual analogue scale (VAS) were compared. Correlation between absolute improvement in individual symptom scores at 1-year postoperative was performed. RESULTS: One-hundred fifty-eight of 201 patients met inclusion criteria giving a response rate of 78%. The average age was 49.4 (range 18-80) with a male-to-female ratio of 1.1:1. The preoperative leading mean symptom scores were postnasal drip (5.8 +/- 0.3), nasal obstruction (5.7 +/- 0.3), and facial congestion (5.1 +/- 0.3). These symptoms were also the most prevalent with 82%, 84%, and 79% of patients reporting these symptoms, respectively. Postoperative symptom improvements were significant (P < .0001) across all RSTF domains except fever. The highest percentage improvement was seen with facial congestion (93%), nasal obstruction (92%), and postnasal drip (85%). Multivariate analysis revealed significant (P < .0001) high correlation between improvements of facial pain/pressure with facial congestion (R = 0.72), facial congestion with nasal obstruction (R = 0.65), and facial pain/pressure with headache (R = 0.72). CONCLUSION: The top three RSTF symptoms were postnasal drip, nasal obstruction, and facial congestion in terms of prevalence and severity. Symptom scores improved after FESS. Of these symptoms, the degree of improvement of facial pain/pressure, facial congestion, nasal obstruction, and headache are highly correlated.

Advances in imaging of the paranasal sinuses.

Imaging technology has played a significant role in the diagnosis and management of sinonasal disorders. Plain sinus films are almost exclusively replaced by CT in the work-up for inflammatory sinus disease. MRI provides complementary information to CT in cases of sinonasal and skull-base neoplasms. The evolution of endoscopic surgical techniques for the paranasal sinuses and skull base is made possible by the parallel advancement of imaging technologies. Recent advances that are currently in clinical use have included multidetector row CT scanners and computer image-guidance systems for surgery. Three-dimensional CT angiography, image-guided CT-MR fusion, and intraoperative image-guidance are new techniques that are currently being evaluated. As imaging technology continues to advance, so does the capability to treat diseases beyond the sinuses and skull base with minimally invasive, endoscopic approaches.