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Most cited (updated monthly)

  • Progress in semiconductor diamond photodetectors and MEMS sensors

    Meiyong Liao

    Diamond with an ultra-wide bandgap shows intrinsic performance that is extraordinarily superior to those of the currently available wide-bandgap semiconductors for deep-ultraviolet (DUV) photoelectronics and microelectromechanical systems (MEMS). The wide-bandgap energy of diamond offers the intrinsic advantage for solar-blind detection of DUV light. The recent progress in high-quality single-crystal diamond growth, doping, and devices design have led to the development of solar-blind DUV detectors satisfying the requirement of high Sensitivity, high Signal-to-Noise ratio, high spectral Selectivity, high Speed, and high Stability. On the other hand, the outstanding mechanical hardness, chemical inertness, and intrinsic low mechanical loss of diamond enable the development of MEMS sensors with boosted sensitivity and robustness. The micromachining technologies for diamond developed in these years have opened the avenue for the fabrication of high-quality single-crystal diamond mechanical resonators. In this review, we report on the recent progress in diamond DUV detectors and MEMS sensors, which includes the device principles, design, fabrication, micromachining of diamond, and devices physics. The potential applications of these sensors and a perspective are also described.

    Single-crystal diamond;
    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Diamond with nitrogen: states, control, and applications

    Yuting Zheng,
    Chengming Li,
    Jinlong Liu,
    Junjun Wei,
    Haitao Ye

    The burgeoning multi-field applications of diamond concurrently bring up a foremost consideration associated with nitrogen. Ubiquitous nitrogen in both natural and artificial diamond in most cases as disruptive impurity is undesirable for diamond material properties, eg deterioration in electrical performance. However, the feat of this most common element-nitrogen, can change diamond growth evolution, endow diamond fancy colors and even give quantum technology a solid boost. This perspective reviews the understanding and progress of nitrogen in diamond including natural occurring gemstones and their synthetic counterparts formed by high temperature high pressure (HPHT) and chemical vapor deposition (CVD) methods. The review paper covers a variety of topics ranging from the basis of physical state of nitrogen and its related defects as well as the resulting effects in diamond (including nitrogen termination on diamond surface), to precise control of nitrogen incorporation associated with selective post-treatments and finally to the practical utilization. Among the multitudinous potential nitrogen related centers, the nitrogen-vacancy (NV) defects in diamond have attracted particular interest and are still ceaselessly drawing extensive attentions for quantum frontiers advance.

    nitrogen-related defect;
    post treatment;
    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Diamond as the heat spreader for the thermal dissipation of GaN-based electronic devices

    Liwen Sang

    With the increasing power density and reduced size of the GaN-based electronic power converters, the heat dissipation in the devices becomes the key issue toward the real applications. Diamond, with the highest thermal conductivity among all the natural materials, is of the interest for integration with GaN to dissipate the generated heat from the channel of the AlGaN/GaN high electron mobility transistors (HEMTs). Current techniques involve three strategies to fabricate the GaN-on-diamond wafers: bonding of GaN with diamond, epitaxial growth of diamond on GaN, and epitaxial growth of GaN on diamond. As a result of the large lattice mismatch and thermal mismatch, the integration of GaN-on-diamond wafer is suffered from stress, bow, crack, rough interfaces, and large thermal boundary resistance. The interfaces with transition or buffer layers impede the heat flow from the device channel and greatly influence the device performance. In this review, we summarize the three different techniques to achieve the GaN-on-diamond wafers for the fabrication of AlGaN/GaN HEMTs. The problems and challenges of each method are discussed. In addition, the effective thermal boundary resistance between GaN and diamond, which characterizes the heat concentration, is analyzed with regard to different integration and measurement methods.

    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Coessential-connection by microwave plasma chemical vapor deposition: a common process towards wafer scale single crystal diamond

    Guoyang Shu,
    Bing Dai,
    Andrey Bolshakov,
    Weihua Wang,
    Yang Wang,
    Kang Liu,
    Jiwen Zhao,
    Jiecai Han,
    Jiaqi Zhu

    Large size single crystal diamond (SCD) wafer has been strongly desired for various of advanced applications, while two major potential approaches, including mosaic growth and heteroepitaxy based on chemical vapor deposition method, are both stuck with respective technical barriers. This paper reveals and summarizes the essential commonality of the two schemes, and denominates the concept of “coessential-connection” (CC) growth. Such generalized concept involved the nature of the single crystal and polycrystalline diamond film deposition with similar mechanism and processes. The principle of CC growth process with detailed classification was elaborated, and influence of nucleus size and orientation mismatch was clarified, which is regarded as the core problem of large area SCD film growth via coessential-connection process.

    Single crystal diamond;
    crystal growth;
    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Properties, mechanism and applications of diamond as an antibacterial material

    Aude Cumont,
    Andrew R. Pitt,
    Peter A. Lambert,
    Marco R. Oggioni,
    Haitao Ye

    Antibiotic resistance in bacteria is a current threat causing an increasing number of infections of difficult clinical management. While the overuse and misuse of antibiotics are investigated to reduce them, the need for alternatives to approaches is rising. Carbon-based materials shown recent moderate to high antibacterial properties and diamond, thanks to its superior mechanical, tribological, electrical, chemical and biological quality is a choice material to investigate for safe antibacterial films, coatings and particles. Here, the antibacterial properties of diamond films, nanodiamonds, DLC films and a comprehensive list of the composites developed from them are discussed along with a summary of the bacterial strains used and the most efficient composition and/or concentration discovered. In a later stage, the mechanisms of action and the parameters that are believed to influence them are discussed and finally, an overview of the biomedical and food industry applications is given.

    surface functionalisation;
    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Progress of structural and electronic properties of diamond: a mini review

    Hongchao Yang,
    Yandong Ma,
    Ying Dai

    Diamond is of great importance for scientific and practical applications. It is the hardest natural material and holds potential applications in mechanics, electronics and photonics. Over the past few decades, great efforts have been paid for exploring its nature both experimentally and theoretically. Most of the recent studies on diamond are focused on their geometry stability and structural properties, while the research on electronic properties is relatively limited. Here, the recent research advances on diamond from a theoretical perspective are presented. In this mini review, we emphasize the recent breakthroughs related to the geometric and electronic properties of diamond, as well as the promising strategies for tuning their electronic properties, such as doping and constructing heterostructure. We then discuss its potential applications in electronic and optoelectronic devices. Finally, the challenges and opportunities in this field are also provided.

    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Recent progress in diamond radiation detectors

    T. Shimaoka,
    S. Koizumi,
    J. H.,

    This paper reviews recent progress in diamond radiation detectors. Diamond is an ultra-wide gap (5.5 eV) semiconducting material which has several ideal properties for radiation detectors, such as solar blindness, high temperature operation, and fast response. Furthermore, diamond has near tissue-equivalence due to its low atomic number (Z = 6) and chemical stability due to its strong covalent bonds. Because of these features, diamond has long been used as a radiation detector in the fields of nuclear engineering, nuclear fusion, high energy physics and medical therapy. Until the 1990s, most of the research was conducted using selected high purity natural diamonds. Since the 2000s, the detector characteristics of synthetic diamond detectors have been greatly improved by achieving high purity diamond by microwave plasma enhanced chemical vapor deposition (CVD). Single-crystal CVD diamonds present best characteristics for spectroscopy in diamond radiation detectors. For applications requiring large sensitive areas, polycrystalline CVD diamond is mostly used. Heteroepitaxial diamond detectors are a promising alternative to increase the area of spectroscopic diamond radiation detectors. For applications in extreme environments, high radiation flux which leads to polarization effects is a crucial issue. Even with diamond, which has excellent radiation hardness, degradation of detector characteristics due to irradiation is inevitable. Detectors designed with small carrier travel distances, such as membrane diamond detectors and three-dimensional diamond radiation detectors, are effective ways to mitigate the degradation.

    Radiation hardness;
    high temperature operation;
    medical application;
    high energy physics;
    beam monitor
    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Room temperature direct bonding of diamond and InGaP in atmospheric air

    Jianbo Liang,
    Yuji Nakamura,
    Yutaka Ohno,
    Yasuo Shimizu,
    Yasuyoshi Nagai,
    Hongxing Wang,
    Naoteru Shigekawa

    A new technique of diamond and InGaP room temperature bonding in atmospheric air is reported. Diamond substrate cleaned with H2SO4/H2O2 mixture solution is bonded to InGaP exposed after removing the GaAs layer by the H2SO4/H2O2/H2O mixture solution. The bonding interface is free from interfacial voids and mechanical cracks. An atomic intermixing layer with a thickness of about 8 nm is formed at the bonding interface, which is composed of C, In, Ga, P, and O atoms. After annealing at 400 °C, no exfoliation occurred along the bonding interface. An increase of about 2 nm in the thickness of the atomic intermixing layer is observed, which plays a role in alleviating the thermal stress caused by the difference of the thermal expansion coefficient between diamond and InGaP. The bonding interface demonstrates high thermal stability to device fabrication processes. This bonding method has a large potential for bonding large diameter diamond and semiconductor materials.

    Diamond atmospheric air room temperature bonding;
    heat dissipation;
    atmospheric air;
    interfacial microstructure;
    thermal boundary conductance
    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Diamond quantum sensors: from physics to applications on condensed matter research

    Kin On Ho,
    Yang Shen,
    Yiu Yung Pang,
    Wai Kuen Leung,
    Nan Zhao,
    Sen Yang

    Single qubit in solid-state materials recently emerges as a versatile platform for quantum information. Among them, the nitrogen vacancy (NV) centre in diamond has become a powerful tool in quantum sensing for detecting various physics parameters, including electric and magnetic fields, temperature, force, strain, with ultimate precision and resolutions. It has been widely used in different conditions, from samples in ambient to samples in ultra-high pressure and low temperature. It can detect quantum phase transitions as well as neuron activities. Here we give a general review on both the physics of the sensing mechanism and protocols and applications.

    quantum sensor;
    nitrogen vacancy centre;
    NV sensing;
    material research;
    Functional Diamond
    Volume 1, Issue 1 (2021)
  • Diamane: design, synthesis, properties, and challenges

    Guowen Qin,
    Lailei Wu,
    Huiyang Gou

    Diamane, the two-dimensional counterpart of diamond, is achieved from bi-layer graphene (BLG) or few-layer graphene (FLG) through surface chemical adsorption or high-pressure technology. Diamane with interlayer sp3 bonding is found to have excellent heat transfer, ultra-low friction, high natural frequency, and tunable band gap, which shows the potential technological and industrial applications in nano-photonics, ultrasensitive resonator-based sensors, and improved wear resistance. In this review, we summarize the structure character, synthesis strategies, and physical properties of different diamanes, including hydrogenated diamane (HD), fluorinated diamane (FD), and pristine diamane (PD). In addition, we discuss the effect of functional groups, element doping, and stacking order on the physical properties of diamane. Finally, the remaining challenges and future opportunities for the further development of diamane are addressed.

    Two dimensional diamond;
    Varied stacking and electronic strcture;
    Diamane with different functional group;
    Chemicaland physical properties
    Functional Diamond
    Volume 1, Issue 1 (2021)