The theory making it possible to rather accurately predict a complete set of characteristics (signals, noises, and photoelectric parameters) inherent to all components of the photodiode-based focal ...plane array (FPA) under design and optimize its parameters has been developed. The theory relies on a new approach to the determination of FPA irradiance, which ensures its calculations at any shape of the diaphragm in the light-insulating shield. Both staring and scanning FPAs, the latter of which operate under the condition of time delay and accumulation, are discussed. The theory has been verified using a 320 × 256 FPA. The calculated dependences of the signals and noises of photoelectric components are compared with the experimental values obtained at different accumulation times and background irradiation temperatures. The theoretical data are revealed to be in complete agreement with the experiment, confirming the model validity. The theory will be undoubtedly useful for designers, manufacturers, and users of FPAs. The model can easily be extended to systems with FPAs.
SWIR ADP 320 × 256 FPAs based on
p
–
i
–
n
photodiodes in InGaAs heterostructures have been developed and investigated. The typical InGaAs/InP PIN heterostructures are formed by Metal Organic Vapor ...Phase Epitaxy (MOVPE) on
n
+
type InP substrates. The InGaAs/InP PIN photodiodes performance have been estimated by measuring current-voltage characteristics. APD arrays are designed using a mesa-passivated avalanche photodiode device array of
p
–
i
–
n
junctions in heterostructure with common absorption and multiplication regions. The optimal operating point for managing avalanche application depended on various factors has been started at 15 V bias and the multiplication coefficient was of 2–4.
Using an analytical model of the avalanche heterophotodiode (AHPhD), principles of selection of its optimal structure are given. The model is based on analytical expressions for the field of the ...avalanche breakdown of the
p
–
n
heterostructure and the interband tunnel current in it, which determines the minimum noise level in the AHPhDs based on direct bandgap semiconductors. To reduce the tunnel current, it is necessary to use a structure with separated absorption and multiplication regions. This approach allows one to analytically determine parameters of the structure in which the latter is implemented. In addition, it enables one to analytically determine such parameters and structures of “low–high–low” type that simultaneously provide both the minimum tunnel current and the minimum avalanche noise factor.
A comparative analysis of the correlators of steady-state thermal and photoinduced stochastic fields (SFs) of concentrations and currents of mobile charge carriers in IR photodiodes and homogeneous ...semiconductors is presented. It is demonstrated that the correlators of thermal and photoinduced SFs of concentrations of mobile charge carriers are determined using conceptually identical expressions for any structure of the
p
–
n
junction and arbitrary polarity of applied voltage whereas the correlators of the SFs of photoinduced and dark currents are determined using conceptually identical expressions only for the reverse-biased
p
–
n
junction with a relatively wide base.
Relationships, which determine requirements for the resistance of the inversion layer for decreasing the influence of the guard ring on the dark current and photodiode noisess and allow obtaining the ...specified intercoupling coefficient between photosensitive elements in multielement photodiodes, are given. It is shown that dependences of the current of the guard ring on the bias voltage and the charge on the Si–SiO
2
interface in the presence of the inversion layer satisfy the current generation model in the space-charge region of the current. The resistance of the inversion layer increase with an increase in the bias voltage in accordance with the relationship
R
u
∼
V
1.5
.
The results of investigation of profiles formed by ion-beam etching of semiconductor structures through a photolithographic mask are presented. The minimum dimensions of unmasked regions on the ...surfaces of two studied structures are 2 and 5 μm, respectively. It is demonstrated that the etching rate reduces with reduction in the width of the unmasked gap. The effect of reflection of the ion beam from vertical walls formed during etching may be used for fabrication of submicron separating mesaregions.
The temperature dependence of the minority charge carriers diffusion length in the active photosensitive layer of a matrix photodetector based on MCT heteroepitaxial structure grown by molecular beam ...epitaxy is studied.
A különböző nyomhagyó eszközzel elkövetett rongálások kapcsán lefoglalt festékanyagok vizsgálata különös szakértelmet és speciális műszereket igényel. Az ilyen jellegű büntetőügyekben végzett ...vizsgálatok a Nemzeti Szakértői és Kutatóközpont (NSZKK) vegyész- és fizikus szakértőinek kompetenciakörébe tartoznak. Az alábbiakban a munkafolyamatok során fellépő nehézségeket és a hatóságokkal történő együttműködés szerepét gyakorlati példákon keresztül mutatjuk be.
U ovome preglednom radu dan je uvid u život i rad doajena znanosti o zračenju i zaštite od zračenja u Hrvatskoj do 1945. godine. Efektivni počeci znanosti o zračenju, pa tako i zaštite od zračenja na ...području Hrvatske sežu čak do kraja 19. stoljeća. Fizičari i kemičari bili su među prvima mogućim žrtvama izloženosti ionizirajućem zračenju, pa su tako i bili prvi koji su upozoravali na štetne učinke radijacije na žive organizme.
Pretraživanje dostupnih arhiva i poznate literature nije samo rasvijetlilo život i rad doajena znanosti o zračenju već je omogućilo sistematičan uvid u do sada nepoznate detalje važne za povijest i razvoj znanosti o zračenju, zaštite od zračenja, kao i o medicinskoj fi zici. Sve to pokazuje da Hrvatska od samoga početka ne samo da slijedi najsuvremenije znanstvene spoznaje iz tih područja, već i njima aktivno pridonosi.
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