Skip to main content

For an AlGaAs/GaAs heterojunction with n-AlGaAs doped to 2 × 1018 cm-3 and a thickness of 40 nm. Calculate the pinch-off voltage if the dielectric constant of the AlGaAs is 12.3.


46. For an AlGaAs/GaAs heterojunction with n-AlGaAs doped to 2 × 1018 cm-3 and a thickness of 40 nm. Calculate the pinch-off voltage if the dielectric constant of the AlGaAs is 12.3.

  1. 1. 0.58 V
  2. 2. -1.0 V
  3. 3. 1.16 V
  4. 4. -0.6 V
Answer: 3

Solution

VP = (q ND d2) / (2ฮต)

Given: q = 1.6e-19, ND = 2e24 m⁻³, d = 40e-9 m, ฮต =  12.3* 8.854e-12 = 1.089e-10.

VP = (1.6e-19 ⋅ 2e24 ⋅ (40e-9)²) / (2 ⋅ 1.089e-10) ≈ 2.35 V.

Browse All Solved Papers (2012 - 2025) →
UGC-NET : Electronics Science Study Material (Subject: 088) →
๐Ÿ“Š MATLAB & ONLINE SIMULATIONS (Web-Based)
๐ŸŽ“ GATE & UGC - NET SOLUTIONS
๐Ÿ“ก WIRELESS & SIGNAL PROCESSING


Contact Us

Name

Email *

Message *

Popular Posts

UGC NET Electronic Science Previous Year Question Papers with Solutions

Download Papers and Solutions Exam Pattern Preparation Tips FAQs More Home / Engineering & Other Exams / UGC NET 2026 PYQ ๐Ÿ“Š Exam Highlights: Electronic Science (88) Feature Details Junior Research Fellowship (JRF) ₹37,000 + HRA per month Eligibility M.Sc/M.Tech in Electronics (55%) Validity of Certificate JRF (3 Years) | Lectureship (Lifetime) ๐Ÿ“ฅ Download UGC NET Electronics PDFs Complete collection of previous year question papers, answer keys and explanations for Subject Code 88. Start Downloading ๐Ÿ“‚ View All Question Papers June 2026 - Question Paper Download PDF June 202...
Read more

CMOS Logic Gates: Inverter, NAND, and NOR

CMOS Logic Gates: Inverter, NAND, and NOR Complementary metal–oxide–semiconductor (CMOS) technology forms the backbone of modern digital IC design. Patented by Frank Wanlass in 1963 ( US patent 3,356,858 ), CMOS enables low-power, high-speed, and noise-immune logic circuits. CMOS gates, including inverters, NAND, and NOR, are widely used in both large-scale and small-scale integrated circuits due to their efficiency and versatility. CMOS Inverter A CMOS inverter consists of a complementary pair of PMOS and NMOS transistors. The PMOS transistor connects to the supply voltage V DD , while the NMOS connects to ground. The input voltage V IN controls both gates, and the output voltage V OUT is taken from the connected drains. CMOS inverters are highly energy-efficient and produce minimal heat due to their comple...
Read more

Coherent vs. Non-Coherent Demodulation

  For demodulation In general: 1. Synchronous (coherent) demodulation Receiver generates a local carrier/oscillator . It combines/multiplies the received signal with that carrier. Then a filter extracts the message. Received signal ↓ × Local oscillator ↓ Low-pass filter ↓ Message So yes, carrier multiplication is a common implementation of synchronous demodulation . 2. Asynchronous (non-coherent) demodulation Receiver doesn't need a phase-synchronized local carrier . It uses properties of the received signal itself to recover the information. For ASK , an envelope detector is the classic example: ASK signal ↓ Diode + RC ↓ Envelope ↓ Comparator ↓ Data Modulation Synchronous demodulation Non-coherent/asynchronous demodulation ASK/OOK Local carrier + multiplier Envelope detector AM Product detector Envelope detector FSK Coherent correlator/mixer Frequency discriminator, filters, etc. PSK Local synchronized carrier + multiplier Differential/n...
Read more

Online Simulator for Frequency Modulatiuon and Demodulation

FM Modulation Simulator Frequency Modulation (FM) In Frequency Modulation, the frequency of the carrier signal varies in accordance with the message signal's amplitude. s FM (t) = A c cos(ฯ‰ c t + k f ∫m(t)dt) where ฯ‰ = 2ฯ€f & k f = Frequency Sensitivity Modulation index, ฮฒ = (k f * A m ) / f m Change the parameter values to see the effect. Message Freq (Hz) 1 Carrier Freq (Hz) Message Amplitude (Am) Kf (sensitivity): 50 Perform FM Demodulation ๐Ÿงช Experiment for Students: ...
Read more

OFDM Symbols and Subcarriers Explained

This article explains how OFDM (Orthogonal Frequency Division Multiplexing) symbols and subcarriers work. It covers modulation, mapping symbols to subcarriers, subcarrier frequency spacing, IFFT synthesis, cyclic prefix, and transmission. Step 1: Modulation First, modulate the input bitstream. For example, with 16-QAM , each group of 4 bits maps to one QAM symbol. Suppose we generate a sequence of QAM symbols: s0, s1, s2, s3, s4, s5, …, s63 Step 2: Mapping Symbols to Subcarriers Assume N sub = 8 subcarriers. Each OFDM symbol in the frequency domain contains 8 QAM symbols (one per subcarrier): Mapping (example) OFDM symbol 1 → s0, s1, s2, s3, s4, s5, s6, s7 OFDM symbol 2 → s8, s9, s10, s11, s12, s13, s14, s15 … OFDM sym...
Read more

(Filters) Free MATLAB alternative for signal analysis

Advanced Signal Filters Upload CSV (1st Col) or Audio (WAV, MP3, etc.) Generate Messy Signal (20Hz + 50Hz + 150Hz) No Operation FFT (Spectrum) Amplitude Modulation (AM) Double Sideband Supressed Carrier (DSBSC) Pulse Amplitude Modulation (PAM) Flat Top PAM Filters - LPF, HPF, BPF, Notch Principal Component Analysis (PCA) Cross Spectrum Filter Type: Signal Cleaner ...
Read more

Interactive Sallen-Key filter Simulation (2nd order LPF)

  Sallen-Key Filter Explained: Why It’s the Most Popular Second-Order Low-Pass Filter Sallen-Key Filter Explained: Why It’s the Most Popular Second-Order Low-Pass Filter (With Math) If you're learning analog electronics, active filters, or preparing for engineering interviews and exams, you've probably come across the Sallen-Key filter . But what exactly is it, and why do engineers prefer it over simply cascading RC low-pass filters? Live Interactive Simulator Adjust the component values to see the real-time frequency response (Bode Plot). R1 (kฮฉ): 10 R2 (kฮฉ): 10 C1 (nF): 10 C2 (nF): 10 ...
Read more

Online Simulator for ASK, FSK, and PSK Signal Generation

Interactive Digital Signal Processing (DSP) Tutorial and Simulator for ASK, FSK, and BPSK modulation techniques. Try our new Digital Signal Processing Simulator!   •   Interactive ASK, FSK, and BPSK tools updated for 2025. Start Now Digital Modulation Visualizer: ASK, FSK, & BPSK Simulator Learn and visualize binary modulation techniques (ASK, FSK, BPSK) in real-time with adjustable carrier and sampling parameters. Perfect for DSP students and engineers. ๐Ÿ“ก ASK Simulator ๐Ÿ“ถ FSK Simulator ๐ŸŽš️ BPSK Simulator ๐Ÿ“š More Topics ASK Modulator FSK Modulator BPSK Modulator Demodulation More Topics 1. ASK (Ampli...
Read more