Epitaxial growth of high In-content In0.41Ga0.59N/GaN heterostructure on (11-20) Al2O3 substrate

Growth characteristics of high Indium content InGaN/GaN heterostructure on a-plane (11 (2) over bar0) sapphire substrate by plasma assisted molecular beam epitaxy have been investigated in detail. The structural analysis is carried out by high-resolution X-ray diffraction measurements. A reduction in the lattice constant by 0.15% confirms the highly crystalline nature of the grown GaN film. Field Emission Scanning Electron Microscopy measurements divulged smooth morphology with less hexagonally pitted GaN surface. This high quality MBE grown GaN on (11 (2) over bar0) sapphire is utilized as a template to grow InGaN film with high indium composition (41%). The elemental distribution and thickness of the grown film is ascertained by Secondary Ion Mass Spectroscopy which demonstrates a sharp interface between the grown structure. The photoluminescence emission spectrum shows a sharp near band edge emission of GaN at 3.42 eV along with a broad band emission related to defects and near band edge emission of InGaN (1.9 +/- 0.05 eV) at room temperature. This study provides a new insight into the structural quality of In-rich InGaN/GaN based heterostructures on a-plane sapphire, which could be useful to develop highly-efficient nitride solar cell devices

Joint Indian Chest Society-National College of Chest Physicians (India) guidelines for spirometry

Although a simple and useful pulmonary function test, spirometry remains underutilized in India. The Indian Chest Society and National College of Chest Physicians (India) jointly supported an expert group to provide recommendations for spirometry in India. Based on a scientific grading of available published evidence, as well as other international recommendations, we propose a consensus statement for planning, performing and interpreting spirometry in a systematic manner across all levels of healthcare in India. We stress the use of standard equipment, and the need for quality control, to optimize testing. Important technical requirements for patient selection, and proper conduct of the vital capacity maneuver, are outlined. A brief algorithm to interpret and report spirometric data using minimal and most important variables is presented. The use of statistically valid lower limits of normality during interpretation is emphasized, and a listing of Indian reference equations is provided for this purpose. Other important issues such as peak expiratory flow, bronchodilator reversibility testing, and technician training are also discussed. We hope that this document will improve use of spirometry in a standardized fashion across diverse settings in India