LEDs are optoelectronic devices that make pn junctions from compound materials. It has the electrical properties of a pn junction device: IV, CV, and optical: spectral response, luminescence, directional, time, and thermal properties. This article will give you a detailed introduction.
1, LED electrical characteristics
1.1 IV characteristics
Characterize the main parameters of the LED chip pn junction preparation performance. The IV characteristics of LEDs have non-linear, rectifying properties: unidirectional conductivity, that is, the application of a positive bias exhibits low contact resistance, and vice versa.
As shown above:
(1) Positive dead zone: (Fig. oa or oa' segment) Point a is the turn-on voltage for V0. When V < Va, the applied electric field overcomes a lot of potential field due to carrier diffusion, and R is very Large; turn-on voltage is different for different LEDs, GaAs is 1V, red GaAsP is 1.2V, GaP is 1.8V, and GaN is 2.5V.
(2) Forward working area: current IF is exponential with applied voltage
IF = IS (e qVF/KT –1) -------------------------IS
Is the reverse saturation current. When V>0, the positive working area IF of V>VF rises with the VF index.
IF = IS e qVF/KT
(3) Reverse dead zone: When V<0, pn junction plus reverse bias voltage V= - VR, when reverse leakage current IR (V= -5V), GaP is 0V and GaN is 10uA.
(4) Reverse breakdown region V<- VR, VR is called reverse breakdown voltage; VR voltage corresponds to IR is reverse leakage current. When the reverse bias voltage is increased such that V < - VR, a sudden increase in IR occurs and a breakdown occurs. The reverse breakdown voltage VR of various LEDs is also different due to the type of compound material used.
1.2 CV characteristics
Since the LED chip has 9×9mil (250×250um), 10×10mil, 11×11mil (280×280um), 12×12mil (300×300um), the pn junction area is different, which makes the junction capacitance (zero). Bias) C≈n+pf or so. The CV characteristics are quadratic (see Figure 2). The 1 MHZ AC signal was measured with a CV characteristic tester.
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Original title of structure:
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