Experimental Analysis and a New Theoretical Model for Anomalously High Ideality Factors (n ≫ 2.0) in GaN-based p-n Junction Diodes

2003 ◽  
Vol 798 ◽  
Author(s):  
Jay M. Shah ◽  
Yunli Li ◽  
Thomas Gessmann ◽  
E. Fred Schubert
Keyword(s):  
Ideality Factor ◽  
Device Simulation ◽  
Superlattice Structure ◽  
In Series ◽  
Bulk Gan ◽  
Expected Values ◽  
Junction Diode ◽  
The One ◽  
P Type ◽  
Junction Structure

ABSTRACTDiode ideality factors of 2.0–8.0 have been reported in GaN-based p-n junctions. These values are much higher than the expected values of 1.0–2.0 as per the Sah-Noyce-Shockley theory. We propose a fundamentally new model for the high ideality factors obtained in GaN-based diodes. This model is based on the effect of moderately doped unipolar heterojunctions as well as metal–semiconductor junctions in series with the p-n junction. A relation for the effective ideality factor of a system of junctions is developed. A detailed experimental study is performed on diodes fabricated from two different structures, a bulk GaN p-n junction structure and a p-n junction structure incorporating a p-type AlGaN/GaN superlattice. Bulk GaN p-n junction diode displays an ideality factor of 6.9, whereas the one with the superlattice structure displays an ideality factor of 4.0. In addition, device simulation results further strengthen the model by showing that moderately doped unipolar heterojunctions are rectifying and increase the effective ideality factor of a p-n junction structure.

Novel Poly-Si/GaN Vertical Heterojunction Diode

2015 ◽  
Vol 821-823 ◽  
pp. 1015-1018
Author(s):  
Kenta Emori ◽  
Toshiharu Marui ◽  
Yuji Saito ◽  
Wei Ni ◽  
Yasushi Nakajima ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Barrier Height ◽  
Epitaxial Layer ◽  
Ideality Factor ◽  
Polycrystalline Silicon ◽  
Experimental Results ◽  
Electrical Characteristics ◽  
Heterojunction Diode ◽  
Bulk Gan ◽  
P Type

We previously reported a unipolar mode p+-polycrystalline silicon (poly-Si)/4H-SiC heterojunction diode (SiC-HJD) [1-3]. In this work, we demonstrate a poly-Si/GaN vertical unipolar heterojunction diode (GaN-HJD) based on numerical simulation and experimental results. The GaN-HJD is expected to control the electrical characteristics of both Schottky action with a p-type poly-Si and ohmic action with an n-type poly-Si. We investigated the detailed physics of the GaN-HJD between p+Si and n+Si by numerical simulation. The GaN-HJD was also fabricated with p+-type polycrystalline silicon on an n--type epitaxial layer on bulk GaN substrates. The measured barrier height of the GaN-HJD was 0.79 eV and the ideality factor was 1.10.

scholarly journals Impact of Etching Time on Ideality Factor and Dynamic Resistance of Porous Silicon Prepared by Electrochemical Etching (ECE)

2017 ◽  
Vol 72 ◽  
pp. 28-36 ◽  
Author(s):  
Hasan A. Hadi
Keyword(s):  
Porous Silicon ◽  
Ideality Factor ◽  
Thermal Evaporation ◽  
Crystalline Silicon ◽  
Electrochemical Etching ◽  
Etching Time ◽  
Dynamic Resistance ◽  
Current Voltage ◽  
The One ◽  
P Type

In this work, porous silicon layers were fabricated on p-type crystalline silicon wafers using electrochemical etching ECE process. Al films were deposited onto porous layer /Si wafers by thermal evaporation to form rectifying junction. An investigation of the dependence on applied etching time to formed PS layer was studied. Effect etching time on the electrical properties of porous silicon is checked using Current–voltage I–V characteristics. The ideality factor and dynamic resistances are found to be large than the one and 20 (kΩ) respectively by the analysis of the dark I–V characteristics of Al/PS/p-Si heterojunction.

Growth and Measurement of Mg Doped AlGaN/GaN Superlattice with Low Resistiviy

2012 ◽  
Vol 549 ◽  
pp. 274-277
Author(s):  
Jun Feng Chen
Keyword(s):  
Al Content ◽  
Superlattice Structure ◽  
Annealing Conditions ◽  
Great Progress ◽  
Bulk Gan ◽  
P Type ◽  
Relationship Of ◽  
The Relationship ◽  
Mg Doped

Although the research of bulk GaN material has take great progress in recent years, while the high quality of p-type GaN material still is an obstacle to fabricate the HBT and LD devices. In this paper we growth a group of Mg doped AlGaN/GaN superlattices under variant conditions. The Hall, AFM, PL and HR-XRD measurement are taken to find the relationship of sample quality with the superlattice structure, growth and annealing conditions. The results show that the period length of about 9nm and Al content of 30% is the optimal structure; the best annealing temperature under tmosphere is about 540°C to 580°C. At last the p-type AlGaN/GaN superlattice with resistivity of 0.31Ω•cm is fabricated which can be utilize for the contact layers of blue LEDs.

Analytic Form Solution of the Direct Position Analysis of a Wide Family of Three-Legged Parallel Manipulators

2005 ◽  
Vol 128 (1) ◽  
pp. 264-271 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Analytic Form ◽  
Parallel Manipulators ◽  
Analytical Form ◽  
Form Solution ◽  
Kinematic Chains ◽  
Position Analysis ◽  
In Series ◽  
The One ◽  
Generic Structures ◽  
Wide Family

A wide family of parallel manipulators (PMs) is the one that groups all PMs with three legs where the legs become kinematic chains constituted of a passive spherical pair (S) in series with either a passive prismatic pair (P) or a passive revolute pair (R) when the actuators are locked. The topologies of the structures generated by these manipulators, when the actuators are locked, are ten. Two out of these topologies are the SR-2PS topology (one SR leg and two PS legs) and the SP-2RS topology (one SP leg and two RS legs). This paper presents two algorithms. The first one determines all the assembly modes of the SR-2PS structures. The second one determines all the assembly modes of the SP-2RS structures. The presented algorithms can be applied without changes to solve, in analytical form, the direct position analysis (DPA) of all the parallel manipulators that generate a SR-2PS structure or a SP-2RS structure when the actuators are locked. In particular, the closure equations of two generic structures, one of type SR-2PS and the other of type SP-2RS, are written. The eliminants of the two systems of equations are determined and the solution procedures are presented. Finally, the proposed procedures are applied to real cases. This work demonstrates that (i) the DPA solutions of any PM that becomes a SR-2PS structure are at most eight, and (ii) the DPA solutions of any PM that becomes a SP-2RS structure are at most sixteen.

Ohmic Contacts to p-Type InGaAs/InP with a Graded Bandgap Heterobarrier

1993 ◽  
Vol 318 ◽  
Author(s):  
Patrick W. Leech ◽  
Geoffrey K. Reeves
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Rutherford Backscattering Spectrometry ◽  
Specific Contact Resistance ◽  
Superlattice Structure ◽  
Specific Contact ◽  
P Type ◽  
Metal Layers ◽  
Anneal Temperature ◽  
Graded Bandgap

ABSTRACTOhmic contacts to p-type InP with an In0.47Ga0.53As buffer layer and an interposed superlattice of 50 Å In0.47Ga0.53As/ 50 Å InP have been investigated. Initial studies of contacts to In0.47Ga0.53As/ InP without the superlattice structure have shown that Pd/Zn/Pd/Au metallization produced a lower specific contact resistance (pc = 1.1 × 10−4 Ω cm2) than Pd/Ge/Au, and over a wider range of anneal temperature than Au/Zn/Au. The incorporation of the superlattice in the p-In0.47Ga0.53As/ InP structure resulted in Pd/Zn/Pd/Au contacts with pc of 3.2 × 10−5 Ω cm2 as-deposited and 7.5 × 10−6 Ω.cm2 after a 500 °C anneal. The presence of Pd/Zn in the metallization was shown as important in reducing pc. Significant intermixing of the metal layers and In0.47Ga0.53As occured at ≥ 350 °C, as revealed by Rutherford backscattering spectrometry.

scholarly journals The city as a theatre of characters. John Hejduk’s Masques

2021 ◽  
Vol 9 (2) ◽  
pp. 51
Author(s):  
Luca Cardani
Keyword(s):  
Design Research ◽  
Strong Connection ◽  
Theoretical Design ◽  
In Series ◽  
Place Of Origin ◽  
The One ◽  
The City ◽  
General Work ◽  
Different Parts

The architectural work of John Hejduk (1929-2000) is marked by theoretical-design research, collected in series with titles and periods. Among these series the one entitled Masques, developed since about 1979, can be considered the nucleus of his research on the architecture of the city and the place of origin of his language of construction later developed in his realized buildings. This paper analyses the dense network of references and analogies established by Hejduk to create his Masques, trying to fix its origin in the idea of the city as a theatre of characters composed of architecture. Starting from the name chosen for the title of this series, the paper tries to trace the threads that lead from the general work of the various projects of the Masques series, to the reflections and ideas that produced it. Then, it comes back again to the observation of architecture and of a case study (Security, 1989), to understand and explain its meaning and the compositional methods involved into the process of genesis of form. Through the entire work named Masques, and its recognizable link with the buildings and installation realized around the world, Hejduk has built an archive of architectural prototypes ready to construct different parts of the city, thus highlighting the strong connection that his work establishes with reality in order "to conceive it, represent it and finally realize it".

Investigation of Shading Characteristics of Mono-Crystalline and Poly-Crystalline Photovoltaic Modules Connected in Series

2015 ◽  
Vol 785 ◽  
pp. 220-224 ◽  
Author(s):  
Jin Chuan Teo ◽  
Rodney H.G. Tan ◽  
V.H. Mok
Keyword(s):  
Ideality Factor ◽  
Photovoltaic Module ◽  
Partial Shading ◽  
Photovoltaic Modules ◽  
In Series

This paper presents the investigation of partial shading characteristics of mono-crystalline and poly-crystalline photovoltaic module connected in series. Simulink models are developed to assist the investigation to determine the ideality factor for mono-crystalline and poly-crystalline photovoltaic module. Commercially available mono-crystalline and poly-crystalline photovoltaic module are used to extract measurable parameters for the model to study the behaviour of I-V curve. Measurements have been conducted for the investigation includingmono-crystalline only, poly-crystalline only, both unshaded, mono-crystalline shaded and poly-crystalline shaded. This paper contributes to the understanding of partial shading characteristics of different materials presence in photovoltaic string.

Effect of Plating Layers on the Bonding Strength of p-Type Bi–Te Thermoelectric Elements

2021 ◽  
Vol 21 (8) ◽  
pp. 4503-4507
Author(s):  
Seong Min Yun ◽  
Injoon Son ◽  
Sung Hwa Bae
Keyword(s):  
Bonding Strength ◽  
Thermoelectric Module ◽  
Interface Layer ◽  
Ceramic Substrates ◽  
In Series ◽  
Cu Substrates ◽  
Solder Reaction ◽  
P Type ◽  
Substrate Defects ◽  
Solder Layer

In thermoelectric modules, multiple n-type and p-type thermoelectric elements are electrically connected in series on a Cu electrode that is bonded to a ceramic substrate. Defects in the bond between the thermoelectric elements and the Cu electrode could impact the performance of the entire thermoelectric module. This study investigated the effect of plating layers on the bonding strength of p-type Bi–Te thermoelectric elements. Ni and Pd electroplating was applied to Bi–Te thermoelectric elements; further, electroless Ni–P immersion gold (ENIG) plating was applied to Cu electrodes bonded to ceramic substrates. Forming a Pd/Ni electroplating layer on the surface of thermoelectric elements and an ENIG plating layer on the surface of the Cu electrode improved the bonding strength by approximately 3.5 times. When the Pd/Ni and ENIG plating layers were formed on Bi–Te elements and Cu substrates, respectively, the solderability greatly increased; as the solderability increased, the thickness of the diffusion layer formed with the solder layer increased. The improved bonding strength of the Pd/Ni plated thermoelectric element bonded on the ENIG plated substrate is attributed to the enhanced solderability due to the rapid inter-diffusion of Pd and Au into the solder layer and the formation of a stable and non-defected solder reaction interface layer.

scholarly journals Using iron sulphate to form both n-type and p-type pseudo-thermoelectrics: non-hazardous and ‘second life’ thermogalvanic cells

2020 ◽  
Vol 22 (18) ◽  
pp. 6062-6074
Author(s):  
Mark A. Buckingham ◽  
Kristine Laws ◽  
Jason T. Sengel ◽  
Leigh Aldous
Keyword(s):  
Second Life ◽  
Waste Heat ◽  
In Series ◽  
Iron Sulphate ◽  
P Type

Conventional electrically in-series thermogalvanic cells are proven options to chemically convert waste heat into electricity, but often utilise incompatible chemicals. This work reports significantly safer and more robust cell chemistry.

Larval development of ovine Neostrongylus linearis in four experimentally infected mollusc species

1994 ◽  
Vol 68 (3) ◽  
pp. 207-210 ◽  
Author(s):  
M.Y. Manga-González ◽  
M.P. Morrondo-Pelayo
Keyword(s):  
Post Infection ◽  
The Other ◽  
Snail Species ◽  
Intermediate Hosts ◽  
Cepaea Nemoralis ◽  
In Series ◽  
Mollusc Species ◽  
Higher Temperature ◽  
The One ◽  
First Time

AbstractDevelopment of Neostrongylus linearis larvae was studied in the snail intermediate hosts Oestophora (Oestophora) barbula, Oestophorella buvinieri, Cepaea nemoralis and Helix (Cryptomphalus) aspersa. The molluscs of each species, all adults, were divided into groups of 40 for infection purposes. The infection doses for the first two snail species were 90 and 50 first stage larvae (L1) of N. linearis, respectively. For C. nemoralis two batches were tested: one with 200 L1 kept at 19°C and the other with 250 L1 at a temperature of 21°C. The same was done with Helix (C.) aspersa with 200 L1 at a temperature of 21°C, on the one hand and 300 L1 at 24°C on the other. One or two molluscs of each species were killed in series from the 6th day post-infection (p.i.) until the 44th. Percentage values for total larvae (1, 2 and 3) and L3 were higher with the lower dose for C. nemoralis, whilst the same was true with the higher dose in Helix (C.) aspersa. In both cases, the higher temperature appeared to contribute to cycle acceleration. Using one way analysis of variance, statistically significant differences were detected between the species of molluscs tested concerning percentages of L1 which penetrated, total larvae and L3. According to our results, the decreasing order of susceptibility of these species of molluscs as experimental intermediate hosts of N. linearis is: O. buvinieri, Oestophora (O.) barbula, C. nemoralis and Helix (C.) aspersa. It is the first time that Oestophora (O.) barbula and Oestophorella buvinieri have been named as experimental intermediate hosts of N. linearis.

Sign in / Sign up

Export Citation Format

Share Document